02어긋남 분리 — 겹쳐진 텍스트 층의 위치 값이 짧은 시간 동안 어긋났다가 다시 겹쳐지는 버튼

<main class="stage">
<div class="ctagls is-demo" id="ctagls">
  <div class="ctagls__panel">
    <button class="ctagls__btn" id="ctaglsBtn" type="button">
      <span class="ctagls__layer ctagls__layer--a" id="ctaglsA">한정판 구매</span>
      <span class="ctagls__layer ctagls__layer--b" id="ctaglsB" aria-hidden="true">한정판 구매</span>
    </button>
    <span class="ctagls__hint">호버하면 텍스트 층이 잠깐 어긋납니다</span>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// 계산 겹(시드 난수 어긋남)은 JS 에 있다 — 여기는 정적 배치·색만.
@include stage($stage-ink);

.stage { position: relative; }

.ctagls__panel {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-4;
  padding: $sp-5;
  border-radius: $r-card;
  background: $tick-panel;
}

.ctagls__btn {
  position: relative;
  border: 0;
  border-radius: $r-control;
  background: $subject-pink;
  padding: $sp-4 $sp-5;
  cursor: pointer;
  overflow: hidden;
}

.ctagls__layer {
  display: block;
  font-family: inherit;
  font-weight: 700;
  font-size: 16px;
  color: $subject-ink;
  white-space: nowrap;
}

.ctagls__layer--b {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  color: $subject-blue-light;
  mix-blend-mode: screen;
}

.ctagls__hint {
  color: $tick-mute;
  font-size: 12px;
  text-align: center;
}

@media (max-width: 340px) {
  .ctagls__panel { padding: $sp-4; gap: $sp-3; }
  .ctagls__btn { padding: $sp-3 $sp-4; }
  .ctagls__layer { font-size: 14px; }
}

@media (prefers-reduced-motion: reduce) {
  .ctagls__layer { transition: none !important; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.stage {
  position: relative;
}

.ctagls__panel {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  padding: 20px;
  border-radius: 16px;
  background: #231f28;
}

.ctagls__btn {
  position: relative;
  border: 0;
  border-radius: 12px;
  background: #ff9ebb;
  padding: 16px 20px;
  cursor: pointer;
  overflow: hidden;
}

.ctagls__layer {
  display: block;
  font-family: inherit;
  font-weight: 700;
  font-size: 16px;
  color: #17141a;
  white-space: nowrap;
}

.ctagls__layer--b {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #5b8cf8;
  mix-blend-mode: screen;
}

.ctagls__hint {
  color: #9a93a6;
  font-size: 12px;
  text-align: center;
}

@media (max-width: 340px) {
  .ctagls__panel {
    padding: 16px;
    gap: 12px;
  }
  .ctagls__btn {
    padding: 12px 16px;
  }
  .ctagls__layer {
    font-size: 14px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ctagls__layer {
    transition: none !important;
  }
}

(function () {
  var root = document.getElementById('ctagls');
  var btn = document.getElementById('ctaglsBtn');
  var layerA = document.getElementById('ctaglsA');
  var layerB = document.getElementById('ctaglsB');

  // 계산 겹: mulberry32 시드 난수로 어긋남 폭을 매 틱 정하고, 정해진 시간(320ms) 동안
  // TICK 간격으로 흔들다가 마지막엔 반드시 0 으로 되돌린다 — 재생마다 같은 시드로 같은 패턴.
  var SEED = 20260920;
  function mulberry32(a) {
    return function () {
      a |= 0; a = (a + 0x6D2B79F5) | 0;
      var t = Math.imul(a ^ (a >>> 15), 1 | a);
      t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
      return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
    };
  }
  var rng = mulberry32(SEED);
  var DURATION = 320, TICK = 40;
  var glitchTimer = null;

  function runGlitch() {
    if (glitchTimer) { return; }
    var elapsed = 0;
    glitchTimer = setInterval(function () {
      elapsed += TICK;
      if (elapsed >= DURATION) {
        clearInterval(glitchTimer); glitchTimer = null;
        layerA.style.transform = 'translate(0px,0px)';
        layerB.style.transform = 'translate(0px,0px)';
        return;
      }
      var ax = (rng() - 0.5) * 10;
      var ay = (rng() - 0.5) * 4;
      var bx = (rng() - 0.5) * 10;
      var by = (rng() - 0.5) * 4;
      layerA.style.transform = 'translate(' + ax.toFixed(1) + 'px,' + ay.toFixed(1) + 'px)';
      layerB.style.transform = 'translate(' + bx.toFixed(1) + 'px,' + by.toFixed(1) + 'px)';
    }, TICK);
  }

  function wireReal() {
    btn.addEventListener('mouseenter', function () { root.classList.remove('is-demo'); stopAutoplay(); runGlitch(); });
    btn.addEventListener('focus', function () { root.classList.remove('is-demo'); stopAutoplay(); runGlitch(); });
    btn.addEventListener('click', function () { runGlitch(); });
  }
  wireReal();

  var autoplayTimer = null;
  function stopAutoplay() { if (autoplayTimer) { clearInterval(autoplayTimer); autoplayTimer = null; } }
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (!reduce) { autoplayTimer = setInterval(runGlitch, 900); }
})();

import { useEffect, useRef } from "react";
import styles from "./CtaBtnGlitchSplit.module.scss";

export type CtaBtnGlitchSplitProps = {
  color?: string;
};

export default function CtaBtnGlitchSplit({
  color = "#5b8cf8",
}: CtaBtnGlitchSplitProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const btn = root.querySelector<HTMLButtonElement>(`.${styles.btn}`);
    const layerA = root.querySelector<HTMLSpanElement>(`.${styles.layerA}`);
    const layerB = root.querySelector<HTMLSpanElement>(`.${styles.layerB}`);
    if (!btn || !layerA || !layerB) return;

    // 계산 겹: mulberry32 시드 난수로 어긋남 폭을 매 틱 정하고, 정해진 시간(320ms) 동안
    // TICK 간격으로 흔들다가 마지막엔 반드시 0 으로 되돌린다 — 재생마다 같은 시드로 같은 패턴.
    const SEED = 20260920;
    function mulberry32(a: number) {
      return function () {
        a |= 0; a = (a + 0x6d2b79f5) | 0;
        let t = Math.imul(a ^ (a >>> 15), 1 | a);
        t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
        return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
      };
    }
    const rng = mulberry32(SEED);
    const DURATION = 320, TICK = 40;
    let glitchTimer: number | null = null;

    function runGlitch() {
      if (glitchTimer !== null) return;
      let elapsed = 0;
      glitchTimer = window.setInterval(() => {
        elapsed += TICK;
        if (elapsed >= DURATION) {
          if (glitchTimer !== null) { window.clearInterval(glitchTimer); glitchTimer = null; }
          layerA!.style.transform = "translate(0px,0px)";
          layerB!.style.transform = "translate(0px,0px)";
          return;
        }
        const ax = (rng() - 0.5) * 10;
        const ay = (rng() - 0.5) * 4;
        const bx = (rng() - 0.5) * 10;
        const by = (rng() - 0.5) * 4;
        layerA!.style.transform = "translate(" + ax.toFixed(1) + "px," + ay.toFixed(1) + "px)";
        layerB!.style.transform = "translate(" + bx.toFixed(1) + "px," + by.toFixed(1) + "px)";
      }, TICK);
    }

    function onEnter() { stopAutoplay(); runGlitch(); }
    function onClick() { runGlitch(); }
    btn.addEventListener("mouseenter", onEnter);
    btn.addEventListener("focus", onEnter);
    btn.addEventListener("click", onClick);

    let autoplayTimer: number | null = null;
    function stopAutoplay() { if (autoplayTimer !== null) { window.clearInterval(autoplayTimer); autoplayTimer = null; } }
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (!reduce) { autoplayTimer = window.setInterval(runGlitch, 900); }

    return () => {
      stopAutoplay();
      if (glitchTimer !== null) { window.clearInterval(glitchTimer); }
      btn.removeEventListener("mouseenter", onEnter);
      btn.removeEventListener("focus", onEnter);
      btn.removeEventListener("click", onClick);
    };
  }, []);

  return (
    <div ref={rootRef} className={styles.stage}>
      <div className={styles.panel}>
        <button className={styles.btn} type="button">
          <span className={styles.layerA}>한정판 구매</span>
          <span className={styles.layerB} aria-hidden="true" style={{ color }}>한정판 구매</span>
        </button>
        <span className={styles.hint}>호버하면 텍스트 층이 잠깐 어긋납니다</span>
      </div>
    </div>
  );
}