> ## Documentation Index
> Fetch the complete documentation index at: https://hyperframes-fix-nested-composition-media-inpoint.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Weight Wave

> A crest of thickness travels along a headline: each character swells from light to black and leans forward as the wave passes, driven by the wght and slnt variable-font axes rather than by transforms.

export const VariablesExplorer = ({previewSrc, compositionId, compositionSrc, variables, children}) => {
  const SHIKI = {
    punct: {
      color: "rgb(31, 35, 40)",
      "--shiki-dark": "#808080"
    },
    tag: {
      color: "rgb(17, 99, 41)",
      "--shiki-dark": "#569CD6"
    },
    attr: {
      color: "rgb(5, 80, 174)",
      "--shiki-dark": "#9CDCFE"
    },
    equals: {
      color: "rgb(31, 35, 40)",
      "--shiki-dark": "#D4D4D4"
    },
    value: {
      color: "rgb(10, 48, 105)",
      "--shiki-dark": "#CE9178"
    }
  };
  const CSS = `
.hf-ve {
  --ve-fg: #18181b;
  --ve-muted: #71717a;
  --ve-line: #e4e4e7;
  --ve-surface: #ffffff;
  --ve-sunken: #fafafa;
  --ve-hover: #f4f4f5;
  --ve-on-bg: #18181b;
  --ve-on-fg: #ffffff;
  --ve-ring: rgba(24, 24, 27, 0.14);
  --ve-danger: #b42318;
}
:where(html.dark) .hf-ve {
  --ve-fg: #f4f4f5;
  --ve-muted: #a1a1aa;
  --ve-line: #27272a;
  --ve-surface: #18181b;
  --ve-sunken: #131316;
  --ve-hover: #27272a;
  --ve-on-bg: #f4f4f5;
  --ve-on-fg: #18181b;
  --ve-ring: rgba(244, 244, 245, 0.2);
  --ve-danger: #ff9d95;
}

.hf-ve-tabs {
  display: inline-flex;
  gap: 2px;
  padding: 3px;
  border: 1px solid var(--ve-line);
  border-radius: 9999px;
  background: var(--ve-sunken);
}
.hf-ve-tab {
  padding: 4px 12px;
  border-radius: 9999px;
  font-size: 12px;
  font-weight: 500;
  color: var(--ve-muted);
  background: transparent;
}
.hf-ve-tab[data-on="true"] {
  color: var(--ve-fg);
  background: var(--ve-surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.08);
}
.hf-ve-tab:hover:not([data-on="true"]) { color: var(--ve-fg); }

/* Not a grid. A grid row is as tall as its tallest cell, so a five-line snippet
   sat in the preview's 16:9 box with 300px of dead area under it. The inactive
   pane is taken out of flow instead — and stretches left/right rather than to
   inset 0, so the iframe keeps its own height. An iframe resized on every tab
   switch reflows the composition running inside it. */
.hf-ve-frame { position: relative; }
.hf-ve-cell { min-width: 0; }
.hf-ve-cell[data-on="false"] {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  visibility: hidden;
  pointer-events: none;
}
.hf-ve-preview {
  overflow: hidden;
  border: 1px solid var(--ve-line);
  border-radius: 12px;
}
/* CodeBlock carries the page margins (mt-5 mb-8) that separate it from prose,
   which is dead space inside a tab. Element plus two classes out-specifies a
   Tailwind utility without !important. */
.hf-ve-cell > div.code-block { margin: 0; }
/* The snippet wraps; the source does not.
   A value the reader has to read in full should not hide half of itself off the
   right edge, so the snippet pane wraps — what \`\`\`html wrap does for a fence.
   The width reset is the half that matters: the block's own <code> is sized to
   max-content, and content that never meets an edge never wraps.
   Source is left to scroll sideways like every other code block on the site.
   Wrapping it breaks its indentation, and a comment paragraph re-flowed to a
   narrow column reads worse than one the reader can scroll. */
.hf-ve-snippet .shiki,
.hf-ve-snippet .shiki code {
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}
/* A composition source runs to several hundred lines, and an un-capped tab
   pushes the Customize panel off the screen. The cap goes on the scroll box
   rather than the block, so the filename and its copy button stay put; and it
   is a max-height, so a short source still hugs its own content and the dead
   area under it stays gone. */
.hf-ve-cell .code-block pre {
  max-height: 460px;
  overflow: auto;
}
/* Four classes deep because the rule being answered is three
   (\`html:not(.dark) .codeblock-light pre.shiki code\`), and a shorter selector
   silently loses to it. */
.hf-ve .hf-ve-snippet .code-block pre.shiki code {
  width: auto;
  min-width: 0;
}

.hf-ve-panel {
  margin-top: 12px;
  border: 1px solid var(--ve-line);
  border-radius: 12px;
}
.hf-ve-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 16px;
  border-bottom: 1px solid var(--ve-line);
}
.hf-ve-title {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ve-muted);
}
.hf-ve-grid {
  display: grid;
  gap: 16px 28px;
  padding: 16px;
}
@media (min-width: 640px) {
  .hf-ve-grid { grid-template-columns: 1fr 1fr; }
}
.hf-ve-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 6px;
}
.hf-ve-label { font-size: 14px; font-weight: 500; color: var(--ve-fg); }
.hf-ve-value {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  color: var(--ve-muted);
}
.hf-ve-desc {
  margin: 6px 0 0;
  font-size: 12px;
  line-height: 1.45;
  color: var(--ve-muted);
}

.hf-ve-btn {
  padding: 4px 10px;
  border: 1px solid transparent;
  border-radius: 8px;
  font-size: 12px;
  font-weight: 500;
  color: var(--ve-muted);
  background: transparent;
}
.hf-ve-btn:hover:not(:disabled) { color: var(--ve-fg); background: var(--ve-hover); }
.hf-ve-btn:disabled { opacity: 0.4; cursor: default; }

.hf-ve-field {
  width: 100%;
  height: 36px;
  padding: 0 12px;
  border: 1px solid var(--ve-line);
  border-radius: 8px;
  font-size: 14px;
  line-height: 1.4;
  color: var(--ve-fg);
  background: var(--ve-surface);
}
.hf-ve-field::placeholder { color: var(--ve-muted); }
.hf-ve-mono { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 13px; }

/* Focus, once, for every control here. A ring outside the border rather than a
   border colour alone: the border already carries the resting state, so
   recolouring it is a change a reader can miss. Nothing shifts, because the
   ring is a shadow. :focus-visible, so a pointer click does not light it up. */
.hf-ve-field:focus-visible,
.hf-ve-seg-btn:focus-visible,
.hf-ve-tab:focus-visible,
.hf-ve-btn:focus-visible,
.hf-ve-switch:focus-visible,
.hf-ve-swatch:focus-visible {
  outline: none;
  border-color: var(--ve-on-bg);
  box-shadow: 0 0 0 3px var(--ve-ring);
}
/* A range is a track, and ringing the track rings a pill the width of the
   panel. The thumb is the part that has focus, so the thumb is what says so. */
.hf-ve-range:focus-visible { outline: none; }
.hf-ve-range:focus-visible::-webkit-slider-thumb { box-shadow: 0 0 0 4px var(--ve-ring); }
.hf-ve-range:focus-visible::-moz-range-thumb { box-shadow: 0 0 0 4px var(--ve-ring); }
/* Safari still fires :focus for a click on a button, so the pair is kept. */
.hf-ve-field:focus { outline: none; border-color: var(--ve-on-bg); }

/* The enum branch above sends anything past four options here. No shipped item
   does today (every enum in the registry has two to four), so this is styled to
   the point of not looking foreign and no further — the chevron is one neutral
   grey rather than a per-theme pair, because a data URI cannot read a token. */
.hf-ve-select {
  appearance: none;
  -webkit-appearance: none;
  padding-right: 34px;
  background-image: url("data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' fill='none' stroke='%2389898f' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m4 6 4 4 4-4'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 10px center;
  cursor: pointer;
}

.hf-ve-seg {
  display: flex;
  padding: 2px;
  border: 1px solid var(--ve-line);
  border-radius: 8px;
}
.hf-ve-seg-btn {
  flex: 1;
  padding: 4px 8px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 500;
  color: var(--ve-muted);
  background: transparent;
}
.hf-ve-seg-btn:hover:not([data-on="true"]) { color: var(--ve-fg); background: var(--ve-hover); }
.hf-ve-seg-btn[data-on="true"] { color: var(--ve-on-fg); background: var(--ve-on-bg); }

/* A range, rebuilt. \`accent-color\` alone leaves the platform's hairline track,
   which reads as an unstyled browser part next to everything else here. Each
   engine names its parts differently and shares none of them, so the same
   track and thumb are written twice; a selector either engine cannot parse
   drops the whole rule, which is why they are never grouped. */
.hf-ve-range {
  width: 100%;
  height: 20px;
  appearance: none;
  -webkit-appearance: none;
  border: 0;
  border-radius: 9999px;
  background: transparent;
  cursor: pointer;
}
/* --ve-fill is set per render: painting progress on a native track means a
   two-stop gradient, and only the component knows where the value sits. */
.hf-ve-range::-webkit-slider-runnable-track {
  height: 6px;
  border-radius: 9999px;
  background: linear-gradient(
    to right,
    var(--ve-on-bg) var(--ve-fill, 0%),
    var(--ve-line) var(--ve-fill, 0%)
  );
}
.hf-ve-range::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  margin-top: -5px;
  border: 2px solid var(--ve-on-bg);
  border-radius: 9999px;
  background: var(--ve-surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.14);
}
.hf-ve-range::-moz-range-track { height: 6px; border-radius: 9999px; background: var(--ve-line); }
.hf-ve-range::-moz-range-progress { height: 6px; border-radius: 9999px; background: var(--ve-on-bg); }
.hf-ve-range::-moz-range-thumb {
  width: 16px;
  height: 16px;
  border: 2px solid var(--ve-on-bg);
  border-radius: 9999px;
  background: var(--ve-surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.14);
}
/* Hover reads on the part being aimed at rather than on the whole strip: a
   track that darkens under the pointer says "click me and the thumb comes
   here", which is what a native range actually does. */
.hf-ve-range:hover::-webkit-slider-thumb { border-color: var(--ve-fg); }
.hf-ve-range:hover::-moz-range-thumb { border-color: var(--ve-fg); }

/* The number control, and the three things it used to leave unsaid.
 *
 * It could not say where the range ends, so a reader dragging \`stroke_width\`
 * had no idea whether 12 was nearly nothing or nearly everything: the ends now
 * carry min and max.
 *
 * It could not say where the author left the knob, which is the one reference
 * point a panel built around deviating from the author's choice needs: a mark
 * on the track is the default, and a double click puts the value back on it.
 *
 * And it printed the value in the label row, a fixed distance from a thumb that
 * moves, so reading a drag meant looking in two places at once. The value rides
 * the thumb instead.
 *
 * Still a real <input type="range">. Every custom slider on the web reimplements
 * keyboard stepping, touch, and the screen-reader contract, and most of them do
 * one of the three badly; none of what is added here needed the element
 * replaced. Nothing moves that a finger is not moving: the value tracks the
 * pointer because it is the pointer's own readout, and the only transition is
 * the colour one every other control here shares. */
.hf-ve-slider {
  display: grid;
  gap: 1px;
}
.hf-ve-ruler {
  position: relative;
  height: 17px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 11px;
  font-variant-numeric: tabular-nums;
  line-height: 17px;
  color: var(--ve-muted);
}
.hf-ve-bound {
  position: absolute;
  top: 0;
}
.hf-ve-bound[data-end="min"] { left: 0; }
.hf-ve-bound[data-end="max"] { right: 0; }
/* An end steps aside rather than being overprinted by the value arriving on
   top of it. Visibility, not opacity: there is no fade here, the label is
   either the thing being read or it is out of the way. */
.hf-ve-ruler[data-near="min"] .hf-ve-bound[data-end="min"],
.hf-ve-ruler[data-near="max"] .hf-ve-bound[data-end="max"] {
  visibility: hidden;
}
/* translateX is centring, not motion: the readout is as wide as its own digits
   and has to hang half of that either side of the thumb. */
.hf-ve-readout {
  position: absolute;
  top: 0;
  left: calc(var(--ve-fill, 0%) + var(--ve-fill-nudge, 0px));
  transform: translateX(-50%);
  color: var(--ve-fg);
  font-weight: 600;
  white-space: nowrap;
}
.hf-ve-track {
  position: relative;
  display: block;
}
.hf-ve-range { display: block; }
.hf-ve-default {
  position: absolute;
  top: 5px;
  left: calc(var(--ve-default, 50%) + var(--ve-default-nudge, 0px));
  width: 2px;
  height: 10px;
  margin-left: -1px;
  border-radius: 1px;
  background: var(--ve-muted);
  pointer-events: none;
}

/* A switch, for the boolean type. It used to fall through to the text input at
   the end of control(), which asked the reader to type the word "true". */
.hf-ve-switch {
  display: inline-flex;
  align-items: center;
  width: 40px;
  height: 24px;
  padding: 2px;
  border: 1px solid var(--ve-line);
  border-radius: 9999px;
  background: var(--ve-sunken);
  cursor: pointer;
}
.hf-ve-switch[data-on="true"] { border-color: var(--ve-on-bg); background: var(--ve-on-bg); }
.hf-ve-switch-dot {
  width: 18px;
  height: 18px;
  border-radius: 9999px;
  background: var(--ve-surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.18);
}
.hf-ve-switch[data-on="true"] .hf-ve-switch-dot {
  background: var(--ve-on-fg);
  transform: translateX(16px);
}

/* The SVG import control: the same text field, with a way to fill it.
 *
 * The whole block is the drop target, not just the field, so a file let go over
 * the button lands too. It says so by taking the same border colour a focused
 * field takes, which is the one feedback channel this panel has left.
 *
 * A bare <input type="file"> is unlabelled, unstyleable and reads as "No file
 * chosen" next to controls that carry their own value, so the real input is
 * taken out of the layout and the tab order and a button in front of it is what
 * a reader sees and what a keyboard reaches. Hidden with size and opacity
 * rather than display:none, because an input that is not rendered at all is one
 * some browsers decline to open a picker for. */
.hf-ve-drop {
  display: grid;
  gap: 8px;
}
.hf-ve-drop[data-over="true"] .hf-ve-dropzone {
  border-color: var(--ve-on-bg);
  border-style: solid;
}

/* The import is the action almost everyone wants: a reader arrives with a
   shape, not with path data. A dashed target reads as "put a file here" on
   sight, where a button beneath a field of coordinates read as an afterthought
   to the coordinates. */
.hf-ve-dropzone {
  display: grid;
  justify-items: center;
  gap: 6px;
  padding: 18px 12px;
  border: 1px dashed var(--ve-line);
  border-radius: 10px;
  background: var(--ve-surface);
  text-align: center;
}
.hf-ve-dropzone .hf-ve-btn {
  padding: 7px 16px;
  font-size: 13px;
  color: var(--ve-fg);
  border-color: var(--ve-line);
  background: var(--ve-bg);
}
.hf-ve-dropzone .hf-ve-btn:hover:not(:disabled) { background: var(--ve-hover); }

/* Path data stays reachable, but a reader has to ask for it. A native details
   element rather than our own toggle, so it opens with the keyboard and is
   announced as expandable without any wiring. */
.hf-ve-advanced > summary {
  font-size: 12px;
  color: var(--ve-muted);
  cursor: pointer;
  list-style: none;
  padding: 2px 0;
}
.hf-ve-advanced > summary::-webkit-details-marker { display: none; }
.hf-ve-advanced > summary::before { content: "▸ "; }
.hf-ve-advanced[open] > summary::before { content: "▾ "; }
.hf-ve-advanced > summary:hover { color: var(--ve-fg); }
.hf-ve-advanced .hf-ve-field { margin-top: 6px; }
.hf-ve-file {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}
.hf-ve-note {
  margin: 0;
  min-width: 0;
  font-size: 12px;
  line-height: 1.4;
  color: var(--ve-muted);
}
.hf-ve-note[data-tone="error"] { color: var(--ve-danger); }
.hf-ve-note[data-tone="ok"] { color: var(--ve-fg); }

.hf-ve-swatch {
  width: 40px;
  height: 32px;
  flex-shrink: 0;
  padding: 2px;
  border: 1px solid var(--ve-line);
  border-radius: 8px;
  background: var(--ve-surface);
  cursor: pointer;
}

/* Nothing here moves.
 *
 * A press-down scale on every button and field, a scale-in on the tab panes, a
 * springing switch knob and a growing slider thumb were all flourish: the
 * control had already told you what it did by changing colour, and the motion
 * was a second, slower answer to a question already settled. What is left is
 * one colour transition, short enough to read as immediate and long enough not
 * to flicker. A control here may change colour; it does not move.
 *
 * Which is also why there is no prefers-reduced-motion block any more. There is
 * no motion left to reduce. */
.hf-ve-tint {
  transition:
    background-color 100ms ease,
    border-color 100ms ease,
    color 100ms ease;
}
`;
  const isSvgPathData = value => typeof value === "string" && (/^\s*[Mm]\s*-?[\d.]/).test(value);
  const parsePathData = d => {
    const source = String(d);
    const arity = {
      M: 2,
      L: 2,
      H: 1,
      V: 1,
      C: 6,
      S: 4,
      Q: 4,
      T: 2,
      A: 7,
      Z: 0
    };
    const commands = [];
    let at = 0;
    let code = "";
    const separator = () => {
      while (at < source.length && (/[\s,]/).test(source[at])) at += 1;
    };
    const digits = () => {
      while (at < source.length && source[at] >= "0" && source[at] <= "9") at += 1;
    };
    const number = () => {
      separator();
      const start = at;
      if (source[at] === "+" || source[at] === "-") at += 1;
      digits();
      if (source[at] === ".") {
        at += 1;
        digits();
      }
      if (source[at] === "e" || source[at] === "E") {
        at += 1;
        if (source[at] === "+" || source[at] === "-") at += 1;
        digits();
      }
      const text = source.slice(start, at);
      const value = Number(text);
      if (text === "" || !Number.isFinite(value)) {
        throw new Error(`expected a number at character ${start + 1}`);
      }
      return value;
    };
    const flag = () => {
      separator();
      const character = source[at];
      if (character !== "0" && character !== "1") {
        throw new Error(`expected an arc flag at character ${at + 1}`);
      }
      at += 1;
      return Number(character);
    };
    separator();
    while (at < source.length) {
      const character = source[at];
      if ((/[a-zA-Z]/).test(character)) {
        if (arity[character.toUpperCase()] === undefined) {
          throw new Error(`unknown command "${character}"`);
        }
        code = character;
        at += 1;
      } else if (code === "") {
        throw new Error("path data must open with a command");
      } else if (code === "M" || code === "m") {
        code = code === "M" ? "L" : "l";
      } else if (code === "Z" || code === "z") {
        throw new Error(`expected a command at character ${at + 1}`);
      }
      const letter = code.toUpperCase();
      const args = [];
      if (letter === "A") {
        args.push(number(), number(), number(), flag(), flag(), number(), number());
      } else {
        for (let taken = 0; taken < arity[letter]; taken += 1) args.push(number());
      }
      commands.push({
        code,
        args
      });
      separator();
    }
    if (commands.length === 0) throw new Error("path data is empty");
    return commands;
  };
  const normalisePathData = commands => {
    const out = [];
    let x = 0;
    let y = 0;
    let startX = 0;
    let startY = 0;
    let cubicControl = null;
    let quadraticControl = null;
    for (const {code, args} of commands) {
      const letter = code.toUpperCase();
      const relative = code !== letter;
      const dx = relative ? x : 0;
      const dy = relative ? y : 0;
      const pairs = values => {
        const mapped = [];
        for (let index = 0; index + 1 < values.length; index += 2) {
          mapped.push(values[index] + dx, values[index + 1] + dy);
        }
        return mapped;
      };
      let nextCubic = null;
      let nextQuadratic = null;
      if (letter === "M") {
        const [px, py] = pairs(args);
        out.push({
          code: "M",
          args: [px, py]
        });
        x = px;
        y = py;
        startX = px;
        startY = py;
      } else if (letter === "L") {
        const [px, py] = pairs(args);
        out.push({
          code: "L",
          args: [px, py]
        });
        x = px;
        y = py;
      } else if (letter === "H") {
        x = args[0] + dx;
        out.push({
          code: "L",
          args: [x, y]
        });
      } else if (letter === "V") {
        y = args[0] + dy;
        out.push({
          code: "L",
          args: [x, y]
        });
      } else if (letter === "C") {
        const points = pairs(args);
        out.push({
          code: "C",
          args: points
        });
        nextCubic = [points[2], points[3]];
        x = points[4];
        y = points[5];
      } else if (letter === "S") {
        const points = pairs(args);
        const first = cubicControl ? [2 * x - cubicControl[0], 2 * y - cubicControl[1]] : [x, y];
        out.push({
          code: "C",
          args: [...first, ...points]
        });
        nextCubic = [points[0], points[1]];
        x = points[2];
        y = points[3];
      } else if (letter === "Q") {
        const points = pairs(args);
        out.push({
          code: "Q",
          args: points
        });
        nextQuadratic = [points[0], points[1]];
        x = points[2];
        y = points[3];
      } else if (letter === "T") {
        const points = pairs(args);
        const control = quadraticControl ? [2 * x - quadraticControl[0], 2 * y - quadraticControl[1]] : [x, y];
        out.push({
          code: "Q",
          args: [...control, ...points]
        });
        nextQuadratic = control;
        x = points[0];
        y = points[1];
      } else if (letter === "A") {
        const endX = args[5] + dx;
        const endY = args[6] + dy;
        out.push(...arcToCubics(x, y, args[0], args[1], args[2], args[3], args[4], endX, endY));
        x = endX;
        y = endY;
      } else if (letter === "Z") {
        out.push({
          code: "Z",
          args: []
        });
        x = startX;
        y = startY;
      }
      cubicControl = nextCubic;
      quadraticControl = nextQuadratic;
    }
    return out;
  };
  const arcToCubics = (x1, y1, rx, ry, rotation, largeArc, sweep, x2, y2) => {
    if (x1 === x2 && y1 === y2) return [];
    let radiusX = Math.abs(rx);
    let radiusY = Math.abs(ry);
    if (radiusX === 0 || radiusY === 0) return [{
      code: "L",
      args: [x2, y2]
    }];
    const phi = rotation * Math.PI / 180;
    const cosPhi = Math.cos(phi);
    const sinPhi = Math.sin(phi);
    const midX = (x1 - x2) / 2;
    const midY = (y1 - y2) / 2;
    const primeX = cosPhi * midX + sinPhi * midY;
    const primeY = -sinPhi * midX + cosPhi * midY;
    const oversize = primeX * primeX / (radiusX * radiusX) + primeY * primeY / (radiusY * radiusY);
    if (oversize > 1) {
      const grow = Math.sqrt(oversize);
      radiusX *= grow;
      radiusY *= grow;
    }
    const denominator = radiusX * radiusX * primeY * primeY + radiusY * radiusY * primeX * primeX;
    const numerator = radiusX * radiusX * radiusY * radiusY - radiusX * radiusX * primeY * primeY - radiusY * radiusY * primeX * primeX;
    const factor = (largeArc === sweep ? -1 : 1) * Math.sqrt(Math.max(0, numerator) / denominator);
    const centrePrimeX = factor * radiusX * primeY / radiusY;
    const centrePrimeY = -factor * radiusY * primeX / radiusX;
    const centreX = cosPhi * centrePrimeX - sinPhi * centrePrimeY + (x1 + x2) / 2;
    const centreY = sinPhi * centrePrimeX + cosPhi * centrePrimeY + (y1 + y2) / 2;
    const angle = (ux, uy, vx, vy) => {
      const length = Math.hypot(ux, uy) * Math.hypot(vx, vy);
      const cosine = length === 0 ? 1 : Math.min(1, Math.max(-1, (ux * vx + uy * vy) / length));
      return (ux * vy - uy * vx < 0 ? -1 : 1) * Math.acos(cosine);
    };
    const fromX = (primeX - centrePrimeX) / radiusX;
    const fromY = (primeY - centrePrimeY) / radiusY;
    const toX = (-primeX - centrePrimeX) / radiusX;
    const toY = (-primeY - centrePrimeY) / radiusY;
    const start = angle(1, 0, fromX, fromY);
    let sweptAngle = angle(fromX, fromY, toX, toY);
    if (!sweep && sweptAngle > 0) sweptAngle -= 2 * Math.PI;
    if (sweep && sweptAngle < 0) sweptAngle += 2 * Math.PI;
    const steps = Math.max(1, Math.ceil(Math.abs(sweptAngle) / (Math.PI / 2)));
    const step = sweptAngle / steps;
    const handle = 4 / 3 * Math.tan(step / 4);
    const at = t => [centreX + radiusX * Math.cos(t) * cosPhi - radiusY * Math.sin(t) * sinPhi, centreY + radiusX * Math.cos(t) * sinPhi + radiusY * Math.sin(t) * cosPhi];
    const slope = t => [-radiusX * Math.sin(t) * cosPhi - radiusY * Math.cos(t) * sinPhi, -radiusX * Math.sin(t) * sinPhi + radiusY * Math.cos(t) * cosPhi];
    const out = [];
    for (let index = 0; index < steps; index += 1) {
      const from = start + index * step;
      const to = from + step;
      const [ax, ay] = at(from);
      const [bx, by] = at(to);
      const [aSlopeX, aSlopeY] = slope(from);
      const [bSlopeX, bSlopeY] = slope(to);
      out.push({
        code: "C",
        args: [ax + handle * aSlopeX, ay + handle * aSlopeY, bx - handle * bSlopeX, by - handle * bSlopeY, bx, by]
      });
    }
    const last = out[out.length - 1];
    last.args[4] = x2;
    last.args[5] = y2;
    return out;
  };
  const transformPathData = (segments, matrix) => segments.map(({code, args}) => {
    const moved = [];
    for (let index = 0; index + 1 < args.length; index += 2) {
      const x = args[index];
      const y = args[index + 1];
      moved.push(matrix.a * x + matrix.c * y + matrix.e, matrix.b * x + matrix.d * y + matrix.f);
    }
    return {
      code,
      args: moved
    };
  });
  const fitMatrix = (source, target) => {
    const chosen = Math.min(target.width / source.width, target.height / source.height);
    const scale = Number.isFinite(chosen) && chosen > 0 ? chosen : 1;
    return {
      a: scale,
      b: 0,
      c: 0,
      d: scale,
      e: target.x + target.width / 2 - (source.x + source.width / 2) * scale,
      f: target.y + target.height / 2 - (source.y + source.height / 2) * scale
    };
  };
  const printPathData = segments => segments.map(({code, args}) => {
    if (args.length === 0) return code;
    const numbers = args.map(value => {
      const rounded = Math.round(value * 100) / 100;
      return String(Object.is(rounded, -0) ? 0 : rounded);
    });
    return `${code} ${numbers.join(" ")}`;
  }).join(" ");
  const shapePathData = (tag, attrs) => {
    const number = (name, fallback = 0) => {
      const value = parseFloat(attrs[name]);
      return Number.isFinite(value) ? value : fallback;
    };
    if (tag === "path") {
      const d = typeof attrs.d === "string" ? attrs.d.trim() : "";
      return d === "" ? null : d;
    }
    if (tag === "rect") {
      const width = number("width");
      const height = number("height");
      if (!(width > 0) || !(height > 0)) return null;
      const x = number("x");
      const y = number("y");
      const declaredX = parseFloat(attrs.rx);
      const declaredY = parseFloat(attrs.ry);
      const rawX = Number.isFinite(declaredX) ? declaredX : declaredY;
      const rawY = Number.isFinite(declaredY) ? declaredY : declaredX;
      const rx = Math.min(Math.max(Number.isFinite(rawX) ? rawX : 0, 0), width / 2);
      const ry = Math.min(Math.max(Number.isFinite(rawY) ? rawY : 0, 0), height / 2);
      if (rx === 0 || ry === 0) {
        return `M ${x} ${y} H ${x + width} V ${y + height} H ${x} Z`;
      }
      return [`M ${x + rx} ${y}`, `H ${x + width - rx}`, `A ${rx} ${ry} 0 0 1 ${x + width} ${y + ry}`, `V ${y + height - ry}`, `A ${rx} ${ry} 0 0 1 ${x + width - rx} ${y + height}`, `H ${x + rx}`, `A ${rx} ${ry} 0 0 1 ${x} ${y + height - ry}`, `V ${y + ry}`, `A ${rx} ${ry} 0 0 1 ${x + rx} ${y}`, "Z"].join(" ");
    }
    if (tag === "circle" || tag === "ellipse") {
      const rx = tag === "circle" ? number("r") : number("rx");
      const ry = tag === "circle" ? number("r") : number("ry");
      if (!(rx > 0) || !(ry > 0)) return null;
      const cx = number("cx");
      const cy = number("cy");
      return [`M ${cx - rx} ${cy}`, `A ${rx} ${ry} 0 1 0 ${cx + rx} ${cy}`, `A ${rx} ${ry} 0 1 0 ${cx - rx} ${cy}`, "Z"].join(" ");
    }
    if (tag === "line") {
      const x1 = number("x1");
      const y1 = number("y1");
      const x2 = number("x2");
      const y2 = number("y2");
      if (x1 === x2 && y1 === y2) return null;
      return `M ${x1} ${y1} L ${x2} ${y2}`;
    }
    if (tag === "polyline" || tag === "polygon") {
      const values = String(attrs.points ?? "").trim().split(/[\s,]+/).map(Number).filter(value => Number.isFinite(value));
      if (values.length < 4) return null;
      const steps = [`M ${values[0]} ${values[1]}`];
      for (let index = 2; index + 1 < values.length; index += 2) {
        steps.push(`L ${values[index]} ${values[index + 1]}`);
      }
      if (tag === "polygon") steps.push("Z");
      return steps.join(" ");
    }
    return null;
  };
  const svgToPathData = (svgText, targetPathData, doc = document) => {
    const NS = "http://www.w3.org/2000/svg";
    const parsed = new DOMParser().parseFromString(String(svgText), "image/svg+xml");
    if (parsed.getElementsByTagName("parsererror").length > 0 || !parsed.documentElement || parsed.documentElement.localName !== "svg") {
      throw new Error("That file is not an SVG, or its markup is malformed.");
    }
    const host = doc.createElement("div");
    host.setAttribute("aria-hidden", "true");
    host.style.cssText = "position:fixed;left:-99999px;top:0;width:600px;height:600px;overflow:hidden;";
    const svg = doc.importNode(parsed.documentElement, true);
    host.appendChild(svg);
    doc.body.appendChild(host);
    try {
      const reference = doc.createElementNS(NS, "g");
      svg.appendChild(reference);
      const rootMatrix = reference.getScreenCTM();
      const defining = ["defs", "clipPath", "mask", "symbol", "marker", "pattern"];
      const isDefinition = element => {
        for (let node = element.parentNode; node && node !== svg; node = node.parentNode) {
          if (defining.includes(node.localName)) return true;
        }
        return false;
      };
      const shapes = [...svg.querySelectorAll("path,rect,circle,ellipse,line,polyline,polygon")];
      const segments = [];
      let shapesUsed = 0;
      let firstProblem = null;
      for (const element of shapes) {
        if (isDefinition(element)) continue;
        if (doc.defaultView.getComputedStyle(element).display === "none") continue;
        const attrs = {};
        for (const attribute of element.attributes) attrs[attribute.localName] = attribute.value;
        const d = shapePathData(element.localName, attrs);
        if (d === null) continue;
        let own;
        try {
          own = normalisePathData(parsePathData(d));
        } catch (error) {
          firstProblem = firstProblem ?? error.message;
          continue;
        }
        const matrix = element.getScreenCTM();
        segments.push(...rootMatrix && matrix ? transformPathData(own, rootMatrix.inverse().multiply(matrix)) : own);
        shapesUsed += 1;
      }
      if (segments.length === 0) {
        if (firstProblem) throw new Error(`This SVG has unreadable path data: ${firstProblem}.`);
        const untraceable = ["text", "image", "use"].find(tag => svg.getElementsByTagName(tag).length > 0);
        throw new Error(untraceable ? `This SVG draws with <${untraceable}>, which has no outline to trace. Convert it to paths and try again.` : "This SVG has no shapes to import.");
      }
      const probe = doc.createElementNS(NS, "path");
      svg.appendChild(probe);
      probe.setAttribute("d", printPathData(segments));
      const source = probe.getBBox();
      if (!(source.width > 0) || !(source.height > 0)) {
        if (!(source.width > 0) && !(source.height > 0)) {
          throw new Error("This SVG's shapes have no size.");
        }
      }
      probe.setAttribute("d", String(targetPathData));
      const target = probe.getBBox();
      return {
        d: printPathData(transformPathData(segments, fitMatrix(source, target))),
        shapes: shapesUsed
      };
    } finally {
      host.remove();
    }
  };
  const granularity = value => {
    const decimals = String(value).split(".")[1];
    return decimals ? Number(`1e-${decimals.length}`) : 1;
  };
  const readout = (variable, value) => {
    if (variable.type === "number") return "";
    if (variable.type === "color") return String(value);
    if (variable.type === "enum") {
      const hit = (variable.options ?? []).find(o => o.value === value);
      return hit ? hit.label ?? hit.value : String(value);
    }
    return "";
  };
  const control = (variable, value, onChange, note, onNote, onTyping) => {
    const options = variable.options ?? [];
    if (variable.type === "enum" && options.length > 0 && options.length <= 4) {
      return <div className="hf-ve-seg">
          {options.map(o => <button key={o.value} type="button" data-on={value === o.value} aria-pressed={value === o.value} onClick={() => onChange(o.value)} className="hf-ve-seg-btn hf-ve-tint">
              {o.label ?? o.value}
            </button>)}
        </div>;
    }
    if (variable.type === "enum") {
      return <select className="hf-ve-field hf-ve-select hf-ve-tint" value={value} aria-label={variable.label ?? variable.id} onChange={e => onChange(e.target.value)}>
          {options.map(o => <option key={o.value} value={o.value}>
              {o.label ?? o.value}
            </option>)}
        </select>;
    }
    if (variable.type === "number") {
      const min = Number(variable.min);
      const max = Number(variable.max);
      const unit = variable.unit ?? "";
      const declaredStep = Number(variable.step);
      const step = declaredStep > 0 ? declaredStep : 1;
      const label = variable.label ?? variable.id;
      if (!(Number.isFinite(min) && Number.isFinite(max) && max > min)) {
        return <input type="number" className="hf-ve-field hf-ve-mono hf-ve-tint" value={value} min={Number.isFinite(min) ? min : undefined} max={Number.isFinite(max) ? max : undefined} step={declaredStep > 0 ? declaredStep : granularity(variable.default)} aria-label={label} onChange={e => {
          const next = Number(e.target.value);
          if (e.target.value !== "" && Number.isFinite(next)) onChange(next);
        }} />;
      }
      const at = n => Math.min(1, Math.max(0, (Number(n) - min) / (max - min)));
      const now = at(value);
      const authored = at(variable.default);
      const place = fraction => ({
        offset: `${fraction * 100}%`,
        nudge: `${(0.5 - fraction) * 16}px`
      });
      const value_ = place(now);
      const default_ = place(authored);
      const grain = event => {
        event.currentTarget.step = event.shiftKey ? step / 10 : step;
      };
      return <div className="hf-ve-slider" style={{
        "--ve-fill": value_.offset,
        "--ve-fill-nudge": value_.nudge,
        "--ve-default": default_.offset,
        "--ve-default-nudge": default_.nudge
      }}>
          {}
          <div className="hf-ve-ruler" data-near={now < 0.14 ? "min" : now > 0.86 ? "max" : ""} aria-hidden="true">
            <span className="hf-ve-bound" data-end="min">
              {min}
            </span>
            <span className="hf-ve-bound" data-end="max">
              {max}
            </span>
            <span className="hf-ve-readout">
              {value}
              {unit}
            </span>
          </div>
          <span className="hf-ve-track">
            <input type="range" className="hf-ve-range" min={min} max={max} step={step} value={value} aria-label={label} aria-valuetext={`${value}${unit}`} onChange={e => onChange(Number(e.target.value))} onPointerDown={grain} onKeyDown={grain} onDoubleClick={() => onChange(variable.default)} />
            {}
            {Math.abs(now - authored) > 0.04 && <span className="hf-ve-default" aria-hidden="true" />}
          </span>
        </div>;
    }
    if (variable.type === "boolean") {
      const on = value === true || value === "true";
      return <button type="button" role="switch" aria-checked={on} aria-label={variable.label ?? variable.id} data-on={on} onClick={() => onChange(!on)} className="hf-ve-switch">
          <span className="hf-ve-switch-dot" />
        </button>;
    }
    if (variable.type === "color") {
      return <div className="flex items-center gap-2">
          <input type="color" className="hf-ve-swatch hf-ve-tint" value={value} aria-label={variable.label ?? variable.id} onChange={e => onChange(e.target.value)} />
          <input type="text" className="hf-ve-field hf-ve-mono hf-ve-tint" value={value} onChange={e => onChange(e.target.value)} onFocus={() => onTyping(variable.id)} onBlur={() => onTyping(null)} onKeyDown={e => {
        if (e.key === "Enter") e.currentTarget.blur();
      }} />
        </div>;
    }
    if (isSvgPathData(variable.default)) {
      const fileId = `hf-ve-file-${variable.id}`;
      const noteId = `hf-ve-note-${variable.id}`;
      const receive = file => {
        if (!file) return;
        file.text().then(text => {
          const {d, shapes} = svgToPathData(text, variable.default);
          onChange(d);
          onNote({
            tone: "ok",
            message: `${file.name}: ${shapes} shape${shapes === 1 ? "" : "s"} scaled to fit.`
          });
        }).catch(error => onNote({
          tone: "error",
          message: error.message
        }));
      };
      return <div className="hf-ve-drop" onDragOver={event => {
        event.preventDefault();
        event.currentTarget.dataset.over = "true";
      }} onDragLeave={event => {
        event.currentTarget.dataset.over = "false";
      }} onDrop={event => {
        event.preventDefault();
        event.currentTarget.dataset.over = "false";
        receive(event.dataTransfer.files[0]);
      }}>
          {}
          <div className="hf-ve-dropzone">
            <button type="button" className="hf-ve-btn hf-ve-tint" onClick={() => document.getElementById(fileId).click()}>
              Import SVG
            </button>
            <input id={fileId} type="file" accept=".svg,image/svg+xml" className="hf-ve-file" tabIndex={-1} aria-hidden="true" onChange={event => {
        receive(event.target.files[0]);
        event.target.value = "";
      }} />
            {}
            <p id={noteId} role="status" className="hf-ve-note" data-tone={note ? note.tone : ""}>
              {note ? note.message : "Or drop one here. Scaled to fit and centred."}
            </p>
          </div>
          <details className="hf-ve-advanced">
            <summary>Path data</summary>
            <input type="text" className="hf-ve-field hf-ve-mono hf-ve-tint" value={value} aria-label={variable.label ?? variable.id} onChange={e => onChange(e.target.value)} onFocus={() => onTyping(variable.id)} onBlur={() => onTyping(null)} onKeyDown={e => {
        if (e.key === "Enter") e.currentTarget.blur();
      }} />
          </details>
        </div>;
    }
    return <input type="text" className="hf-ve-field hf-ve-tint" value={value} aria-label={variable.label ?? variable.id} onChange={e => onChange(e.target.value)} onFocus={() => onTyping(variable.id)} onBlur={() => onTyping(null)} onKeyDown={e => {
      if (e.key === "Enter") e.currentTarget.blur();
    }} />;
  };
  const variablesKey = JSON.stringify(variables);
  const defaults = useMemo(() => {
    const built = {};
    for (const v of variables) if (v.default !== undefined) built[v.id] = v.default;
    return built;
  }, [variablesKey]);
  const urlKey = `vars-${compositionId}`;
  const readFromUrl = () => {
    if (typeof window === "undefined") return {};
    try {
      const raw = new URLSearchParams(window.location.search).get(urlKey);
      if (!raw) return {};
      const parsed = JSON.parse(raw);
      if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) return {};
      const declared = new Set(variables.map(v => v.id));
      return Object.fromEntries(Object.entries(parsed).filter(([id]) => declared.has(id)));
    } catch {
      return {};
    }
  };
  const [values, setValues] = useState(() => ({
    ...defaults,
    ...readFromUrl()
  }));
  useEffect(() => {
    const fromUrl = readFromUrl();
    if (Object.keys(fromUrl).length > 0) setValues(current => ({
      ...current,
      ...fromUrl
    }));
  }, []);
  useEffect(() => {
    if (typeof window === "undefined") return;
    const changed = Object.fromEntries(Object.entries(values).filter(([id, value]) => JSON.stringify(value) !== JSON.stringify(defaults[id])));
    const url = new URL(window.location.href);
    if (Object.keys(changed).length === 0) url.searchParams.delete(urlKey); else url.searchParams.set(urlKey, JSON.stringify(changed));
    const next = url.toString();
    if (next !== window.location.href) {
      window.history.replaceState(null, "", next);
      window.dispatchEvent(new CustomEvent("hf-vars-changed"));
    }
  }, [values, defaults, urlKey]);
  const [notes, setNotes] = useState({});
  const [typing, setTyping] = useState(null);
  const posted = useRef(null);
  const [tab, setTab] = useState("preview");
  const frame = useRef(null);
  const bootstrap = ["<!doctype html><html><head><meta charset='utf-8'>", "<style>html,body{margin:0;height:100%;overflow:hidden;background:transparent}", "hyperframes-player{display:block;width:100%;height:100%}</style>", '<script src="https://cdn.jsdelivr.net/npm/@hyperframes/player@0.7/dist/hyperframes-player.global.js"></' + "script>", "</head><body><script>", "(function(){", `  var PAYLOAD = ${JSON.stringify(previewSrc)};`, `  var INITIAL = ${JSON.stringify({
    ...defaults,
    ...readFromUrl()
  })};`, "  var html = null, player = null, poll = null;", "  function withValues(source, values) {", "    var json = JSON.stringify(values);", "    var attr = json.replace(/'/g, '&#39;');", "    var out = source.replace(/\\sdata-variable-values=(?:\"[^\"]*\"|'[^']*')/gi, '');", "    out = out.replace(/(data-composition-src=)/gi, \"data-variable-values='\" + attr + \"' $1\");", "    var tag = '<' + 'script>window.__hfVariables=' + json + ';<' + '/script>';", "    return /<head[^>]*>/i.test(out)", "      ? out.replace(/<head([^>]*)>/i, '<head$1>' + tag)", "      : tag + out;", "  }", "  function arm(resumeAt) {", "    clearInterval(poll);", "    var last = -1, tries = 0, seeked = false;", "    poll = setInterval(function () {", "      if (player.ready) {", "        if (!seeked) { seeked = true; if (resumeAt > 0) player.seek(resumeAt); }", "        player.play();", "      }", "      if (seeked && player.currentTime > 0 && player.currentTime !== last) {", "        clearInterval(poll); return;", "      }", "      last = player.currentTime;", "      if (++tries > 150) clearInterval(poll);", "    }, 100);", "  }", "  function mount(values, resumeAt) {", "    if (html === null) return;", "    player.setAttribute('srcdoc', withValues(html, values));", "    arm(resumeAt || 0);", "  }", "  player = document.createElement('hyperframes-player');", "  player.setAttribute('controls', ''); player.setAttribute('muted', '');", "  document.body.appendChild(player);", "  player.addEventListener('ended', function () { player.seek(0); player.play(); });", "  fetch(PAYLOAD).then(function (r) { return r.json(); }).then(function (d) {", "    html = d.html; mount(INITIAL, 0);", "  }).catch(function (e) {", "    document.body.innerHTML = '<pre style=\"color:#f66;font:12px monospace;padding:12px\">preview unavailable: ' + e + '</pre>';", "  });", "  addEventListener('message', function (event) {", "    var values = event.data && event.data.hfVariables;", "    if (!values) return;", "    mount(values, player.currentTime || 0);", "  });", "})();", "</" + "script></body></html>"].join("");
  useEffect(() => {
    if (typing !== null) return;
    const payload = JSON.stringify(values);
    if (payload === posted.current) return;
    const timer = setTimeout(() => {
      const target = frame.current && frame.current.contentWindow;
      if (!target) return;
      posted.current = payload;
      target.postMessage({
        hfVariables: values
      }, window.location.origin);
    }, 150);
    return () => clearTimeout(timer);
  }, [values, typing]);
  const printed = JSON.stringify(values, null, 2).split("\n").join("\n  ");
  const attributes = [["data-composition-id", `"${compositionId}"`], ["data-composition-src", `"${compositionSrc}"`], ["data-variable-values", `'${printed}'`]];
  const snippetLines = [[[SHIKI.punct, "<"], [SHIKI.tag, "div"]]];
  for (const [name, literal] of attributes) {
    const [head, ...rest] = literal.split("\n");
    snippetLines.push([[SHIKI.attr, `  ${name}`], [SHIKI.equals, "="], [SHIKI.value, head]]);
    for (const line of rest) snippetLines.push([[SHIKI.value, line]]);
  }
  snippetLines.push([[SHIKI.punct, "></"], [SHIKI.tag, "div"], [SHIKI.punct, ">"]]);
  const dirty = variables.some(v => values[v.id] !== defaults[v.id]);
  const installCommand = (() => {
    const base = `npx hyperframes add ${compositionId}`;
    if (!dirty) return base;
    const changed = {};
    for (const v of variables) {
      if (JSON.stringify(values[v.id]) !== JSON.stringify(defaults[v.id])) changed[v.id] = values[v.id];
    }
    return `${base} --vars '${JSON.stringify(changed)}'`;
  })();
  const TABS = [["preview", "Preview"], ...children ? [["code", "Code"]] : [], ["snippet", "Snippet"]];
  return <div className="hf-ve not-prose my-4">
      <style dangerouslySetInnerHTML={{
    __html: CSS
  }} />

      <div className="mb-3 flex items-center gap-3">
        <div className="hf-ve-tabs">
          {TABS.map(([id, label]) => <button key={id} type="button" data-on={tab === id} aria-pressed={tab === id} onClick={() => setTab(id)} className="hf-ve-tab hf-ve-tint">
              {label}
            </button>)}
        </div>
      </div>

      {}
      <div className="hf-ve-frame">
        <div className="hf-ve-cell" data-on={tab === "preview"}>
          <iframe ref={frame} srcDoc={bootstrap} className="hf-ve-preview block aspect-video w-full" title={`${compositionId} preview`} />
        </div>
        {children && <div className="hf-ve-cell" data-on={tab === "code"}>
            {children}
          </div>}
        <div className="hf-ve-cell hf-ve-snippet" data-on={tab === "snippet"}>
          {}
          <CodeBlock filename="Terminal">
            <pre className="shiki shiki-themes github-light-default dark-plus" style={{
    backgroundColor: "rgb(255, 255, 255)",
    "--shiki-dark-bg": "#0B0C0E",
    color: "rgb(31, 35, 40)",
    "--shiki-dark": "#D4D4D4"
  }}>
              <code>
                <span className="line">
                  <span style={SHIKI.value}>{installCommand}</span>
                  {"\n"}
                </span>
              </code>
            </pre>
          </CodeBlock>
          {}
          <CodeBlock filename="index.html">
            <pre className="shiki shiki-themes github-light-default dark-plus" style={{
    backgroundColor: "rgb(255, 255, 255)",
    "--shiki-dark-bg": "#0B0C0E",
    color: "rgb(31, 35, 40)",
    "--shiki-dark": "#D4D4D4"
  }}>
              <code>
                {snippetLines.map((tokens, line) => <span key={line} className="line">
                    {tokens.map(([style, text], token) => <span key={token} style={style}>
                        {text}
                      </span>)}
                    {"\n"}
                  </span>)}
              </code>
            </pre>
          </CodeBlock>
        </div>
      </div>

      <div className="hf-ve-panel">
        <div className="hf-ve-head">
          <span className="hf-ve-title">Customize</span>
          <button type="button" onClick={() => {
    setValues(defaults);
    setNotes({});
  }} disabled={!dirty} className="hf-ve-btn hf-ve-tint">
            Reset
          </button>
        </div>
        <div className="hf-ve-grid">
          {variables.map(v => <div key={v.id}>
              <div className="hf-ve-row">
                <label className="hf-ve-label">{v.label ?? v.id}</label>
                <span className="hf-ve-value">{readout(v, values[v.id])}</span>
              </div>
              {control(v, values[v.id], next => setValues(prev => ({
    ...prev,
    [v.id]: next
  })), notes[v.id], note => setNotes(prev => ({
    ...prev,
    [v.id]: note
  })), setTyping)}
              {v.description && <p className="hf-ve-desc">{v.description}</p>}
            </div>)}
        </div>
      </div>
    </div>;
};

export const InstallCommand = ({command, item}) => {
  const [copied, setCopied] = React.useState(false);
  const [tuned, setTuned] = React.useState("");
  React.useEffect(() => {
    if (!item) return;
    const read = () => {
      try {
        const raw = new URLSearchParams(window.location.search).get(`vars-${item}`);
        if (!raw) return setTuned("");
        const parsed = JSON.parse(raw);
        if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) return setTuned("");
        if (Object.keys(parsed).length === 0) return setTuned("");
        setTuned(` --vars '${JSON.stringify(parsed)}'`);
      } catch {
        setTuned("");
      }
    };
    read();
    window.addEventListener("hf-vars-changed", read);
    window.addEventListener("popstate", read);
    return () => {
      window.removeEventListener("hf-vars-changed", read);
      window.removeEventListener("popstate", read);
    };
  }, [item]);
  const fullCommand = `${command}${tuned}`;
  const copy = async () => {
    try {
      if (navigator.clipboard && window.isSecureContext) {
        await navigator.clipboard.writeText(fullCommand);
      } else {
        const previous = document.activeElement;
        const scratch = document.createElement("textarea");
        scratch.value = fullCommand;
        scratch.setAttribute("readonly", "");
        scratch.style.position = "fixed";
        scratch.style.opacity = "0";
        document.body.appendChild(scratch);
        scratch.select();
        document.execCommand("copy");
        document.body.removeChild(scratch);
        previous?.focus?.();
      }
      setCopied(true);
      setTimeout(() => setCopied(false), 2000);
    } catch {}
  };
  return <div className="hf-install-command not-prose my-4 flex items-stretch overflow-hidden rounded-xl border border-zinc-200 bg-zinc-50 dark:border-zinc-800 dark:bg-zinc-900">
      <code className="flex-1 overflow-x-auto whitespace-nowrap border-r border-zinc-200 px-4 py-3 font-mono text-sm text-zinc-800 dark:border-zinc-800 dark:text-zinc-100">
        {fullCommand}
      </code>
      <button type="button" onClick={copy} data-copied={copied ? "true" : "false"} aria-label={`Copy ${command} to the clipboard`} className="hf-install-copy">
        <svg className="hf-install-copy-clipboard" xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 18 18" fill="none" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
          <path d="M14.25 5.25H7.25C6.14543 5.25 5.25 6.14543 5.25 7.25V14.25C5.25 15.3546 6.14543 16.25 7.25 16.25H14.25C15.3546 16.25 16.25 15.3546 16.25 14.25V7.25C16.25 6.14543 15.3546 5.25 14.25 5.25Z" />
          <path d="M2.80103 11.998L1.77203 5.07397C1.61003 3.98097 2.36403 2.96397 3.45603 2.80197L10.38 1.77297C11.313 1.63397 12.19 2.16297 12.528 3.00097" />
        </svg>
        <svg className="hf-install-copy-check" xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 18 18" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
          <path d="M2.75 9.5L6.5 13.25L15.25 4.5" />
        </svg>
      </button>
      <span className="hf-install-copy-status" role="status" aria-live="polite">
        {copied ? "Copied" : ""}
      </span>
    </div>;
};

<VariablesExplorer previewSrc="/public/catalog/blocks/weight-wave.json" compositionId="weight-wave" compositionSrc="compositions/weight-wave.html" variables={[{"id":"text","type":"string","label":"Headline","default":"PRESSURE MOVES THROUGH TYPE","maxLength":64},{"id":"color","type":"color","label":"Text color","default":"#f5f5f7"},{"id":"background","type":"color","label":"Background","default":"#0b0b0d"},{"id":"weightFrom","type":"number","label":"Weight (rest)","default":400,"min":300,"max":1000,"step":10},{"id":"weightTo","type":"number","label":"Weight (crest)","default":1000,"min":300,"max":1000,"step":10},{"id":"crestWidth","type":"number","label":"Crest width","default":4,"min":1,"max":24,"step":0.5,"unit":"chars"},{"id":"sweepSpeed","type":"number","label":"Sweep speed","default":0.5,"min":0.05,"max":3,"step":0.05,"unit":"passes/s"},{"id":"slant","type":"number","label":"Slant at crest","default":-12,"min":-15,"max":0,"step":0.5,"unit":"deg"},{"id":"direction","type":"enum","label":"Direction","default":"ltr","options":[{"value":"ltr","label":"Left to right"},{"value":"rtl","label":"Right to left"}]}]}>
  ```html weight-wave.html theme={null}
  <!doctype html>
  <html lang="en">
    <head>
      <meta charset="UTF-8" />
      <meta name="viewport" content="width=1920, height=1080" />
      <title>Weight Wave</title>
      <style>
        /*
          Real variable font, bundled locally — a CDN fetch would be a render-time
          network dependency, and a STATIC font would silently render every
          character at one weight (the whole effect vanishes while nothing errors).
          Subset of Recursive (SIL OFL 1.1) with every axis pinned except the two
          this block drives. Ranges below are the font's REAL fvar records, read
          out of the binary: wght 300..1000 (not 100..900) and slnt -15..0. The
          pinned three are MONO 0 (proportional sans, not the monospace face),
          CASL 0 (linear/neutral, not casual) and CRSV 0 (roman letterforms —
          Recursive's 0.5 default swaps in cursive singlestorey forms as soon as
          slnt goes negative, which would pop mid-wave instead of interpolating).
        */
        @font-face {
          font-family: "Recursive Wave";
          font-style: normal;
          font-weight: 300 1000;
          font-display: block;
          src: url("assets/fonts/Recursive-wght-slnt-latin.woff2") format("woff2");
        }
      </style>
      <script src="https://cdn.jsdelivr.net/npm/gsap@3.14.2/dist/gsap.min.js"></script>
      <style>
        *,
        *::before,
        *::after {
          margin: 0;
          padding: 0;
          box-sizing: border-box;
        }
        html,
        body {
          background: transparent;
          overflow: hidden;
        }
        body {
          width: 1920px;
          height: 1080px;
        }

        #ww-root {
          position: relative;
          width: 1920px;
          height: 1080px;
          overflow: hidden;
        }

        /* Full-bleed fill lives on a CHILD: the producer can drop a background
           painted on the composition root itself (frame renders black). */
        #ww-bg {
          position: absolute;
          inset: 0;
          background: var(--background, #0b0b0d);
        }

        #ww-stage {
          position: absolute;
          inset: 0;
          display: flex;
          align-items: center;
          justify-content: center;
        }

        #ww-line {
          display: block;
          width: 1760px;
          text-align: center;
          white-space: pre;
          font-family: "Recursive Wave", sans-serif;
          font-size: 132px;
          line-height: 1.15;
          letter-spacing: 0.005em;
          color: var(--color, #f5f5f7);
          /* Default instance: the resting end of the wave. If the variable font
             fails to load, every glyph stays here and the probe below shouts. */
          font-variation-settings:
            "wght" 400,
            "slnt" 0;
        }

        /* Per-character axis stamping target: no transform, no opacity — the
           letterforms themselves change. */
        .ww-ch {
          display: inline-block;
        }
      </style>
    </head>
    <body>
      <div
        id="ww-root"
        data-composition-id="weight-wave"
        data-start="0"
        data-duration="6"
        data-width="1920"
        data-height="1080"
        data-composition-variables='[
          {"id":"text","type":"string","label":"Headline","default":"PRESSURE MOVES THROUGH TYPE","maxLength":64},
          {"id":"color","type":"color","label":"Text color","default":"#f5f5f7"},
          {"id":"background","type":"color","label":"Background","default":"#0b0b0d"},
          {"id":"weightFrom","type":"number","label":"Weight (rest)","default":400,"min":300,"max":1000,"step":10},
          {"id":"weightTo","type":"number","label":"Weight (crest)","default":1000,"min":300,"max":1000,"step":10},
          {"id":"crestWidth","type":"number","label":"Crest width","default":4,"min":1,"max":24,"step":0.5,"unit":"chars"},
          {"id":"sweepSpeed","type":"number","label":"Sweep speed","default":0.5,"min":0.05,"max":3,"step":0.05,"unit":"passes/s"},
          {"id":"slant","type":"number","label":"Slant at crest","default":-12,"min":-15,"max":0,"step":0.5,"unit":"deg"},
          {"id":"direction","type":"enum","label":"Direction","default":"ltr","options":[{"value":"ltr","label":"Left to right"},{"value":"rtl","label":"Right to left"}]}
        ]'
      >
        <div id="ww-bg"></div>

        <div id="ww-stage" class="clip" data-start="0" data-duration="6" data-track-index="0">
          <div id="ww-line"></div>
        </div>

        <script>
          (function () {
            window.__timelines = window.__timelines || {};

            var FONT_FAMILY = '"Recursive Wave", sans-serif';
            /* The bundled font's real fvar bounds — declared once here, and
               mirrored in the variable min/max above. A slider must not offer a
               weight the font cannot render. */
            var WGHT_MIN = 300;
            var WGHT_MAX = 1000;
            var SLNT_MIN = -15;
            var LINE_MAX_WIDTH = 1760;
            var BASE_FONT_SIZE = 132;
            var MIN_FONT_SIZE = 40;

            var root = document.getElementById("ww-root");
            var line = document.getElementById("ww-line");
            var duration = Number(root.getAttribute("data-duration")) || 6;

            var vars =
              window.__hyperframes && window.__hyperframes.getVariables
                ? window.__hyperframes.getVariables()
                : {};

            function num(value, fallback, min, max) {
              var n = Number(value);
              if (!Number.isFinite(n)) n = fallback;
              return Math.min(max, Math.max(min, n));
            }

            var TEXT =
              typeof vars.text === "string" && vars.text.length
                ? vars.text
                : "PRESSURE MOVES THROUGH TYPE";
            var W_FROM = num(vars.weightFrom, 400, WGHT_MIN, WGHT_MAX);
            var W_TO = num(vars.weightTo, 1000, WGHT_MIN, WGHT_MAX);
            var CREST = num(vars.crestWidth, 4, 1, 24);
            var SPEED = num(vars.sweepSpeed, 0.5, 0.05, 3);
            var SLANT = num(vars.slant, -12, SLNT_MIN, 0);
            var RTL = vars.direction === "rtl";

            /* ── Build one span per character ─────────────────────────────────
               Spaces get a span too, so the crest travels at a constant rate in
               index space and the visual gap between words is honoured. */
            var chars = Array.prototype.slice.call(TEXT);
            var spans = chars.map(function (ch) {
              var el = document.createElement("span");
              el.className = "ww-ch";
              el.textContent = ch;
              line.appendChild(el);
              return el;
            });
            var N = spans.length;

            /* Fit at the HEAVIEST instance so the line never overflows mid-sweep;
               the crest widens glyphs as it passes. */
            var fitCanvas = document.createElement("canvas").getContext("2d");
            var heaviest = Math.max(W_FROM, W_TO);
            var fontSize = BASE_FONT_SIZE;
            while (fontSize > MIN_FONT_SIZE) {
              fitCanvas.font = heaviest + " " + fontSize + "px " + FONT_FAMILY;
              if (fitCanvas.measureText(TEXT).width <= LINE_MAX_WIDTH) break;
              fontSize -= 2;
            }
            line.style.fontSize = fontSize + "px";

            /* ── The wave ─────────────────────────────────────────────────────
               Closed form, no accumulators: every frame's state is a pure
               function of the timeline position p, so a direct seek to frame N
               and playing through to frame N produce identical pixels.

                 crest(p) = -CREST + wrap(p * duration * SPEED) * (N - 1 + 2*CREST)
                 f_i      = clamp(0, 1, 1 - |i - crest| / CREST)
                 wght_i   = round(lerp(W_FROM, W_TO, f_i))
                 slnt_i   = lerp(0, SLANT, f_i)

               Per-character stagger is not a separate mechanism — it falls out of
               the crest's distance to each index. */
            var state = { p: 0 };
            var travel = N - 1 + 2 * CREST;

            function paint() {
              var pass = state.p * duration * SPEED;
              var phase = pass - Math.floor(pass); // wraps cleanly: f_i == 0 at both ends
              var crest = -CREST + phase * travel;
              if (RTL) crest = N - 1 - crest;
              for (var i = 0; i < N; i++) {
                var f = 1 - Math.abs(i - crest) / CREST;
                if (f < 0) f = 0;
                else if (f > 1) f = 1;
                var wght = Math.round(W_FROM + (W_TO - W_FROM) * f);
                var slnt = SLANT * f;
                spans[i].style.fontVariationSettings =
                  '"wght" ' + wght + ', "slnt" ' + slnt.toFixed(2);
              }
            }

            var tl = gsap.timeline({ paused: true });
            tl.to(state, { p: 1, duration: duration, ease: "none", onUpdate: paint }, 0);
            paint();
            window.__timelines["weight-wave"] = tl;

            /* ── The trap, made loud ──────────────────────────────────────────
               A static font (or a failed load) renders every character at one
               weight: the effect is invisible and nothing throws.

               Measuring advance width does NOT detect that here. Recursive is
               DUPLEXED — "HAMBURGEFONSTIV" measures exactly 925px at wght 300 and
               at wght 1000, and identically at slnt 0 and -15. (Nice for layout:
               the headline never reflows as the crest passes. Fatal for a
               width-delta probe, which reads every weight as identical and cries
               wolf on a perfectly healthy font.)

               So rasterize and count ink, which cannot be duplexed away, AND ask
               the font-loading API whether the family is actually there. Both are
               needed: ink alone gives a false PASS when the family is missing,
               because the fallback varies its ink with weight too. */
            function probeAxes() {
              var family = "Recursive Wave";
              var loaded = !!(document.fonts && document.fonts.check('100px "' + family + '"'));
              var c = document.createElement("canvas");
              c.width = 1000;
              c.height = 160;
              var ctx = c.getContext("2d", { willReadFrequently: true });
              function ink(weight) {
                ctx.clearRect(0, 0, c.width, c.height);
                ctx.font = weight + ' 100px "' + family + '"';
                ctx.fillStyle = "#fff";
                ctx.fillText("HAMBURGEFONSTIV", 10, 120);
                var data = ctx.getImageData(0, 0, c.width, c.height).data;
                var n = 0;
                for (var i = 3; i < data.length; i += 4) if (data[i] > 8) n++;
                return n;
              }
              var light = ink(WGHT_MIN);
              var black = ink(WGHT_MAX);
              // Only wght is probed: it is the axis whose absence is measurable
              // from JS, and both axes ship in the same file — if wght is live,
              // the variable font loaded. slnt is verified visually.
              return {
                fontLoaded: loaded,
                wghtLive: black > light * 1.2,
                inkAtMinWeight: light,
                inkAtMaxWeight: black,
              };
            }

            function publishProbe() {
              var status = probeAxes();
              status.ok = status.fontLoaded && status.wghtLive;
              window.__WW_FONT_STATUS = status;
              root.setAttribute("data-ww-font", status.ok ? "ok" : "missing-axes");
              if (!status.ok) {
                console.error(
                  "weight-wave: the variable font is not usable (loaded=" +
                    status.fontLoaded +
                    ", ink at wght " +
                    WGHT_MIN +
                    "=" +
                    status.inkAtMinWeight +
                    " vs " +
                    WGHT_MAX +
                    "=" +
                    status.inkAtMaxWeight +
                    "). assets/fonts/Recursive-wght-slnt-latin.woff2 did not load, or was " +
                    "replaced with a static font — every character will render at one weight.",
                );
              }
            }

            if (document.fonts && document.fonts.ready) {
              document.fonts.ready.then(publishProbe);
            } else {
              publishProbe();
            }
          })();
        </script>
      </div>
    </body>
  </html>
  ```
</VariablesExplorer>

## Install

<InstallCommand command="npx hyperframes add weight-wave" item="weight-wave" />

That writes `compositions/weight-wave.html`, plus 2 supporting files under `compositions/assets/fonts/`.

## Add it to your video

It runs for 6 seconds at 1920×1080. Paste this into your composition:

```html index.html theme={null}
<div
  data-composition-id="weight-wave"
  data-composition-src="compositions/weight-wave.html"
  data-start="0"
  data-duration="6"
  data-track-index="1"
  data-width="1920"
  data-height="1080"
></div>
```

Move it in time with `data-start`. Put it on a different timeline row with
`data-track-index`. See [data attributes](/concepts/data-attributes) for the rest.

## Variables

Every one of these has a default, so the piece works untouched. Set the ones you
want to change on the element:

| Variable     | Default                       | Accepts                                      | What it does |
| ------------ | ----------------------------- | -------------------------------------------- | ------------ |
| `text`       | `PRESSURE MOVES THROUGH TYPE` | string                                       |              |
| `color`      | `#f5f5f7`                     | color                                        |              |
| `background` | `#0b0b0d`                     | color                                        |              |
| `weightFrom` | `400`                         | 300 to 1000, step 10                         |              |
| `weightTo`   | `1000`                        | 300 to 1000, step 10                         |              |
| `crestWidth` | `4`                           | 1chars to 24chars, step 0.5chars             |              |
| `sweepSpeed` | `0.5`                         | 0.05passes/s to 3passes/s, step 0.05passes/s |              |
| `slant`      | `-12`                         | -15deg to 0deg, step 0.5deg                  |              |
| `direction`  | `ltr`                         | `ltr`, `rtl`                                 |              |

Set them with `data-variable-values` on the element that mounts it. These are the
defaults, so this behaves exactly like the preview above until you change one:

```html wrap theme={null}
<div
  data-composition-id="weight-wave"
  data-composition-src="compositions/weight-wave.html"
  data-variable-values='{"text":"PRESSURE MOVES THROUGH TYPE","color":"#f5f5f7","background":"#0b0b0d","weightFrom":400,"weightTo":1000,"crestWidth":4,"sweepSpeed":0.5,"slant":-12,"direction":"ltr"}'
></div>
```

## Source

<Accordion title={`weight-wave.html`}>
  ```html theme={null}
  <!doctype html>
  <html lang="en">
    <head>
      <meta charset="UTF-8" />
      <meta name="viewport" content="width=1920, height=1080" />
      <title>Weight Wave</title>
      <style>
        /*
          Real variable font, bundled locally — a CDN fetch would be a render-time
          network dependency, and a STATIC font would silently render every
          character at one weight (the whole effect vanishes while nothing errors).
          Subset of Recursive (SIL OFL 1.1) with every axis pinned except the two
          this block drives. Ranges below are the font's REAL fvar records, read
          out of the binary: wght 300..1000 (not 100..900) and slnt -15..0. The
          pinned three are MONO 0 (proportional sans, not the monospace face),
          CASL 0 (linear/neutral, not casual) and CRSV 0 (roman letterforms —
          Recursive's 0.5 default swaps in cursive singlestorey forms as soon as
          slnt goes negative, which would pop mid-wave instead of interpolating).
        */
        @font-face {
          font-family: "Recursive Wave";
          font-style: normal;
          font-weight: 300 1000;
          font-display: block;
          src: url("assets/fonts/Recursive-wght-slnt-latin.woff2") format("woff2");
        }
      </style>
      <script src="https://cdn.jsdelivr.net/npm/gsap@3.14.2/dist/gsap.min.js"></script>
      <style>
        *,
        *::before,
        *::after {
          margin: 0;
          padding: 0;
          box-sizing: border-box;
        }
        html,
        body {
          background: transparent;
          overflow: hidden;
        }
        body {
          width: 1920px;
          height: 1080px;
        }

        #ww-root {
          position: relative;
          width: 1920px;
          height: 1080px;
          overflow: hidden;
        }

        /* Full-bleed fill lives on a CHILD: the producer can drop a background
           painted on the composition root itself (frame renders black). */
        #ww-bg {
          position: absolute;
          inset: 0;
          background: var(--background, #0b0b0d);
        }

        #ww-stage {
          position: absolute;
          inset: 0;
          display: flex;
          align-items: center;
          justify-content: center;
        }

        #ww-line {
          display: block;
          width: 1760px;
          text-align: center;
          white-space: pre;
          font-family: "Recursive Wave", sans-serif;
          font-size: 132px;
          line-height: 1.15;
          letter-spacing: 0.005em;
          color: var(--color, #f5f5f7);
          /* Default instance: the resting end of the wave. If the variable font
             fails to load, every glyph stays here and the probe below shouts. */
          font-variation-settings:
            "wght" 400,
            "slnt" 0;
        }

        /* Per-character axis stamping target: no transform, no opacity — the
           letterforms themselves change. */
        .ww-ch {
          display: inline-block;
        }
      </style>
    </head>
    <body>
      <div
        id="ww-root"
        data-composition-id="weight-wave"
        data-start="0"
        data-duration="6"
        data-width="1920"
        data-height="1080"
        data-composition-variables='[
          {"id":"text","type":"string","label":"Headline","default":"PRESSURE MOVES THROUGH TYPE","maxLength":64},
          {"id":"color","type":"color","label":"Text color","default":"#f5f5f7"},
          {"id":"background","type":"color","label":"Background","default":"#0b0b0d"},
          {"id":"weightFrom","type":"number","label":"Weight (rest)","default":400,"min":300,"max":1000,"step":10},
          {"id":"weightTo","type":"number","label":"Weight (crest)","default":1000,"min":300,"max":1000,"step":10},
          {"id":"crestWidth","type":"number","label":"Crest width","default":4,"min":1,"max":24,"step":0.5,"unit":"chars"},
          {"id":"sweepSpeed","type":"number","label":"Sweep speed","default":0.5,"min":0.05,"max":3,"step":0.05,"unit":"passes/s"},
          {"id":"slant","type":"number","label":"Slant at crest","default":-12,"min":-15,"max":0,"step":0.5,"unit":"deg"},
          {"id":"direction","type":"enum","label":"Direction","default":"ltr","options":[{"value":"ltr","label":"Left to right"},{"value":"rtl","label":"Right to left"}]}
        ]'
      >
        <div id="ww-bg"></div>

        <div id="ww-stage" class="clip" data-start="0" data-duration="6" data-track-index="0">
          <div id="ww-line"></div>
        </div>

        <script>
          (function () {
            window.__timelines = window.__timelines || {};

            var FONT_FAMILY = '"Recursive Wave", sans-serif';
            /* The bundled font's real fvar bounds — declared once here, and
               mirrored in the variable min/max above. A slider must not offer a
               weight the font cannot render. */
            var WGHT_MIN = 300;
            var WGHT_MAX = 1000;
            var SLNT_MIN = -15;
            var LINE_MAX_WIDTH = 1760;
            var BASE_FONT_SIZE = 132;
            var MIN_FONT_SIZE = 40;

            var root = document.getElementById("ww-root");
            var line = document.getElementById("ww-line");
            var duration = Number(root.getAttribute("data-duration")) || 6;

            var vars =
              window.__hyperframes && window.__hyperframes.getVariables
                ? window.__hyperframes.getVariables()
                : {};

            function num(value, fallback, min, max) {
              var n = Number(value);
              if (!Number.isFinite(n)) n = fallback;
              return Math.min(max, Math.max(min, n));
            }

            var TEXT =
              typeof vars.text === "string" && vars.text.length
                ? vars.text
                : "PRESSURE MOVES THROUGH TYPE";
            var W_FROM = num(vars.weightFrom, 400, WGHT_MIN, WGHT_MAX);
            var W_TO = num(vars.weightTo, 1000, WGHT_MIN, WGHT_MAX);
            var CREST = num(vars.crestWidth, 4, 1, 24);
            var SPEED = num(vars.sweepSpeed, 0.5, 0.05, 3);
            var SLANT = num(vars.slant, -12, SLNT_MIN, 0);
            var RTL = vars.direction === "rtl";

            /* ── Build one span per character ─────────────────────────────────
               Spaces get a span too, so the crest travels at a constant rate in
               index space and the visual gap between words is honoured. */
            var chars = Array.prototype.slice.call(TEXT);
            var spans = chars.map(function (ch) {
              var el = document.createElement("span");
              el.className = "ww-ch";
              el.textContent = ch;
              line.appendChild(el);
              return el;
            });
            var N = spans.length;

            /* Fit at the HEAVIEST instance so the line never overflows mid-sweep;
               the crest widens glyphs as it passes. */
            var fitCanvas = document.createElement("canvas").getContext("2d");
            var heaviest = Math.max(W_FROM, W_TO);
            var fontSize = BASE_FONT_SIZE;
            while (fontSize > MIN_FONT_SIZE) {
              fitCanvas.font = heaviest + " " + fontSize + "px " + FONT_FAMILY;
              if (fitCanvas.measureText(TEXT).width <= LINE_MAX_WIDTH) break;
              fontSize -= 2;
            }
            line.style.fontSize = fontSize + "px";

            /* ── The wave ─────────────────────────────────────────────────────
               Closed form, no accumulators: every frame's state is a pure
               function of the timeline position p, so a direct seek to frame N
               and playing through to frame N produce identical pixels.

                 crest(p) = -CREST + wrap(p * duration * SPEED) * (N - 1 + 2*CREST)
                 f_i      = clamp(0, 1, 1 - |i - crest| / CREST)
                 wght_i   = round(lerp(W_FROM, W_TO, f_i))
                 slnt_i   = lerp(0, SLANT, f_i)

               Per-character stagger is not a separate mechanism — it falls out of
               the crest's distance to each index. */
            var state = { p: 0 };
            var travel = N - 1 + 2 * CREST;

            function paint() {
              var pass = state.p * duration * SPEED;
              var phase = pass - Math.floor(pass); // wraps cleanly: f_i == 0 at both ends
              var crest = -CREST + phase * travel;
              if (RTL) crest = N - 1 - crest;
              for (var i = 0; i < N; i++) {
                var f = 1 - Math.abs(i - crest) / CREST;
                if (f < 0) f = 0;
                else if (f > 1) f = 1;
                var wght = Math.round(W_FROM + (W_TO - W_FROM) * f);
                var slnt = SLANT * f;
                spans[i].style.fontVariationSettings =
                  '"wght" ' + wght + ', "slnt" ' + slnt.toFixed(2);
              }
            }

            var tl = gsap.timeline({ paused: true });
            tl.to(state, { p: 1, duration: duration, ease: "none", onUpdate: paint }, 0);
            paint();
            window.__timelines["weight-wave"] = tl;

            /* ── The trap, made loud ──────────────────────────────────────────
               A static font (or a failed load) renders every character at one
               weight: the effect is invisible and nothing throws.

               Measuring advance width does NOT detect that here. Recursive is
               DUPLEXED — "HAMBURGEFONSTIV" measures exactly 925px at wght 300 and
               at wght 1000, and identically at slnt 0 and -15. (Nice for layout:
               the headline never reflows as the crest passes. Fatal for a
               width-delta probe, which reads every weight as identical and cries
               wolf on a perfectly healthy font.)

               So rasterize and count ink, which cannot be duplexed away, AND ask
               the font-loading API whether the family is actually there. Both are
               needed: ink alone gives a false PASS when the family is missing,
               because the fallback varies its ink with weight too. */
            function probeAxes() {
              var family = "Recursive Wave";
              var loaded = !!(document.fonts && document.fonts.check('100px "' + family + '"'));
              var c = document.createElement("canvas");
              c.width = 1000;
              c.height = 160;
              var ctx = c.getContext("2d", { willReadFrequently: true });
              function ink(weight) {
                ctx.clearRect(0, 0, c.width, c.height);
                ctx.font = weight + ' 100px "' + family + '"';
                ctx.fillStyle = "#fff";
                ctx.fillText("HAMBURGEFONSTIV", 10, 120);
                var data = ctx.getImageData(0, 0, c.width, c.height).data;
                var n = 0;
                for (var i = 3; i < data.length; i += 4) if (data[i] > 8) n++;
                return n;
              }
              var light = ink(WGHT_MIN);
              var black = ink(WGHT_MAX);
              // Only wght is probed: it is the axis whose absence is measurable
              // from JS, and both axes ship in the same file — if wght is live,
              // the variable font loaded. slnt is verified visually.
              return {
                fontLoaded: loaded,
                wghtLive: black > light * 1.2,
                inkAtMinWeight: light,
                inkAtMaxWeight: black,
              };
            }

            function publishProbe() {
              var status = probeAxes();
              status.ok = status.fontLoaded && status.wghtLive;
              window.__WW_FONT_STATUS = status;
              root.setAttribute("data-ww-font", status.ok ? "ok" : "missing-axes");
              if (!status.ok) {
                console.error(
                  "weight-wave: the variable font is not usable (loaded=" +
                    status.fontLoaded +
                    ", ink at wght " +
                    WGHT_MIN +
                    "=" +
                    status.inkAtMinWeight +
                    " vs " +
                    WGHT_MAX +
                    "=" +
                    status.inkAtMaxWeight +
                    "). assets/fonts/Recursive-wght-slnt-latin.woff2 did not load, or was " +
                    "replaced with a static font — every character will render at one weight.",
                );
              }
            }

            if (document.fonts && document.fonts.ready) {
              document.fonts.ready.then(publishProbe);
            } else {
              publishProbe();
            }
          })();
        </script>
      </div>
    </body>
  </html>
  ```
</Accordion>

Tagged `typography` `kinetic-type` `title` `variable-font` `text`.

## Related topics

* [Browse the complete Catalog](/catalog)
* [Add assets and Catalog items in Studio](/studio/assets-and-blocks)
* [Build a richer composition](/go-further)