Per-Word Crossfade

<!--
  Per-Word Crossfade - remocn typography primitive for HyperFrames.

  Paste the markup, CSS and script into a composition. Drive the timeline
  integration from a paused GSAP timeline so renders remain deterministic.

  Variables. The script reads each one, falls back to the declared default on
  anything missing or unrecognised, and either rewrites the words or writes a
  custom property the CSS below consumes. The timeline recipe at the end is
  untouched by them: it keeps driving one offset and one blur, and these
  decide what that offset and that blur mean on screen.

    - text (string, default "Create once reuse everywhere"): the line to
      animate. It is split on whitespace and every word gets its own span, so
      the stagger picks up the new words with no other change.
    - drift (close | standard | far, default standard): scales the vertical
      offset. close covers half the run, far nearly double, in the same time.
    - blur (soft | standard | heavy, default standard): scales the blur
      radius, from a light haze to a full smear.
    - tone (ink | paper | accent, default ink): word colour. ink is near-black
      for light frames, paper near-white for dark ones, accent rides --brand.

  On every default the result is identical to the original: four near-black
  words drifting 22px up through a 5px blur.
-->

<div
  class="hf-remocn-per-word-crossfade"
  data-composition-variables='[
    { "id": "text", "type": "string", "role": "content", "label": "Text", "description": "The line to animate. It is split on whitespace and every word gets its own span, so the stagger picks up the new words.", "default": "Create once reuse everywhere" },
    { "id": "drift", "type": "enum", "role": "motion", "label": "Drift", "description": "Scales the vertical offset, so the words cover a shorter or longer run in the same time.", "default": "standard", "options": [{ "value": "close", "label": "Close" }, { "value": "standard", "label": "Standard" }, { "value": "far", "label": "Far" }] },
    { "id": "blur", "type": "enum", "role": "style", "label": "Blur", "description": "Scales the blur radius the timeline drives, from a light haze to a full smear.", "default": "standard", "options": [{ "value": "soft", "label": "Soft" }, { "value": "standard", "label": "Standard" }, { "value": "heavy", "label": "Heavy" }] },
    { "id": "tone", "type": "enum", "role": "style", "label": "Tone", "description": "Word colour: ink for light frames, paper for dark ones, accent rides --brand.", "default": "ink", "options": [{ "value": "ink", "label": "Ink" }, { "value": "paper", "label": "Paper" }, { "value": "accent", "label": "Accent" }] }
  ]'
>
  <span>Create</span><span>once</span><span>reuse</span><span>everywhere</span>
</div>

<style>
  .hf-remocn-per-word-crossfade {
    color: var(--hf-word-color, #18181b);
    font-family: Inter, system-ui, sans-serif;
    font-weight: 900;
    letter-spacing: -0.04em;
  }
  .hf-remocn-per-word-crossfade {
    display: inline-flex;
    gap: 12px;
    font-size: 56px;
    line-height: 1;
  }
  .hf-remocn-per-word-crossfade span {
    display: inline-block;
    transform: translate(
        var(--hf-word-x, 0px),
        calc(var(--hf-word-y, 0px) * var(--hf-word-drift, 1))
      )
      scale(var(--hf-word-scale, 1));
    filter: blur(calc(var(--hf-word-blur, 0px) * var(--hf-word-blur-scale, 1)));
    will-change: transform, filter, opacity;
  }
</style>

<script>
  (function () {
    "use strict";

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

    // Unrecognised overrides return to their declared defaults.
    var drifts = { close: 0.5, standard: 1, far: 1.85 };
    var blurScales = { soft: 0.45, standard: 1, heavy: 2.2 };
    var tones = {
      ink: "#18181b",
      paper: "#fafafa",
      accent: "var(--brand, #34d399)",
    };

    function pick(table, value, fallback) {
      return Object.prototype.hasOwnProperty.call(table, value) ? value : fallback;
    }

    var drift = drifts[pick(drifts, vars.drift, "standard")];
    var blurScale = blurScales[pick(blurScales, vars.blur, "standard")];
    var tone = tones[pick(tones, vars.tone, "ink")];

    var text = typeof vars.text === "string" ? vars.text.trim() : "";
    var words = (text || "Create once reuse everywhere").split(/\s+/);

    var roots = document.querySelectorAll(".hf-remocn-per-word-crossfade");
    for (var i = 0; i < roots.length; i += 1) {
      var root = roots[i];
      root.style.setProperty("--hf-word-drift", String(drift));
      root.style.setProperty("--hf-word-blur-scale", String(blurScale));
      root.style.setProperty("--hf-word-color", tone);

      while (root.firstChild) {
        root.removeChild(root.firstChild);
      }
      for (var w = 0; w < words.length; w += 1) {
        var span = document.createElement("span");
        span.textContent = words[w];
        root.appendChild(span);
      }
    }
  })();
</script>

<!--
  Timeline integration:
  tl.fromTo('.hf-remocn-per-word-crossfade span', { opacity: 0, '--hf-word-y': '22px', '--hf-word-scale': 0.92, '--hf-word-blur': '5px' }, { opacity: 1, '--hf-word-y': '0px', '--hf-word-scale': 1, '--hf-word-blur': '0px', duration: 0.3, stagger: 0.055, ease: 'power3.out' }, startTime);
-->