09モーション減時の静止代替

<main class="stage">
  <div class="panel is-demo">
    <div class="panel__row">
      <div class="marquee">
        <div class="marquee__track">
          <span class="marquee__chip">お知らせ</span>
          <span class="marquee__chip">アップデート</span>
          <span class="marquee__chip">イベント</span>
          <span class="marquee__chip" aria-hidden="true">お知らせ</span>
          <span class="marquee__chip" aria-hidden="true">アップデート</span>
          <span class="marquee__chip" aria-hidden="true">イベント</span>
        </div>
      </div>
      <span class="panel__state">
        <span class="panel__state-text panel__state-text--play">再生中</span>
        <span class="panel__state-text panel__state-text--pause">停止中</span>
      </span>
    </div>
    <label class="panel__toggle" aria-hidden="true">
      <span class="panel__toggle-track"><span class="panel__toggle-knob"></span></span>
      <span class="panel__toggle-label">モーションを減らす</span>
    </label>
  </div>
</main>

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

$duration: $dur-loop;
$easing: $ease-spring;
$color: $subject-blue;
$fg: $subject-cream;

@include stage($stage-ink);

.panel {
  display: grid;
  gap: 14px;
  justify-items: center;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}
.panel__row {
  display: grid;
  gap: 8px;
  justify-items: center;
}
.marquee {
  width: min(240px, 70vw);
  overflow: hidden;
}
.marquee__track {
  display: flex;
  width: max-content;
}
.marquee__chip {
  margin-right: 14px;   // 트랙의 gap 대신 — 세트 폭이 정확히 절반이 되어 -50% 이음새가 0px 이 된다
  flex-shrink: 0;
  display: grid;
  place-items: center;
  height: 30px;
  padding: 0 12px;
  border-radius: $r-control;
  background: rgba($fg, .1);
  color: $fg;
  font-weight: 700; font-size: 12px; line-height: 1; font-family: inherit;
}
.panel__state { position: relative; width: 100%; min-width: 84px; height: 16px; }
.panel__state-text {
  position: absolute;
  inset: 0;
  width: 100%;
  text-align: center;
  white-space: nowrap;
  font-weight: 700; font-size: 12px; line-height: 16px; font-family: inherit;
  color: rgba($fg, .7);
}
.panel__toggle { display: flex; align-items: center; gap: 8px; }
.panel__toggle-track {
  position: relative;
  width: 36px;
  height: 20px;
  border-radius: $r-pill;
  background: rgba($fg, .18);
}
.panel__toggle-knob {
  position: absolute;
  top: 2px;
  left: 2px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: $color;
}
.panel__toggle-label {
  font-weight: 600; font-size: 11px; line-height: 1; font-family: inherit;
  color: rgba($fg, .68);
}

// 트랙은 토글이 꺼진 55% 구간까지만 움직이고, 켜진 뒤로는 그 자리에 그대로 멈춘다 —
// 실제 prefers-reduced-motion: reduce 사용자에게 나가는 화면과 같은 정지 상태다
.panel.is-demo .marquee__track { animation: marquee-toggle $duration linear infinite; }
.panel.is-demo .panel__toggle-knob { animation: toggle-knob $duration $easing infinite; }
.panel.is-demo .panel__toggle-track { animation: toggle-track $duration $easing infinite; }
.panel.is-demo .panel__state-text--play { animation: state-play $duration steps(1) infinite; }
.panel.is-demo .panel__state-text--pause { animation: state-pause $duration steps(1) infinite; }

@keyframes marquee-toggle {
  0%       { transform: translateX(0); }
  55%      { transform: translateX(-30%); }
  100%     { transform: translateX(-30%); }
}
@keyframes toggle-knob {
  0%, 50%   { transform: translateX(0); }
  70%, 100% { transform: translateX(16px); }
}
@keyframes toggle-track {
  0%, 50%   { background: rgba($fg, .18); }
  70%, 100% { background: rgba($color, .38); }
}
@keyframes state-play {
  0%, 50%   { opacity: 1; }
  60%, 100% { opacity: 0; }
}
@keyframes state-pause {
  0%, 50%   { opacity: 0; }
  60%, 100% { opacity: 1; }
}

@media (prefers-reduced-motion: reduce) {
  .marquee__track, .panel__toggle-knob, .panel__toggle-track,
  .panel__state-text--play, .panel__state-text--pause {
    animation: none !important;
  }
  .panel.is-demo .marquee__track { transform: translateX(-30%); }
  .panel.is-demo .panel__toggle-knob { transform: translateX(16px); }
  .panel.is-demo .panel__toggle-track { background: rgba($color, .38); }
  .panel.is-demo .panel__state-text--play { opacity: 0; }
  .panel.is-demo .panel__state-text--pause { opacity: 1; }
}

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);
}

.panel {
  display: grid;
  gap: 14px;
  justify-items: center;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

.panel__row {
  display: grid;
  gap: 8px;
  justify-items: center;
}

.marquee {
  width: min(240px, 70vw);
  overflow: hidden;
}

.marquee__track {
  display: flex;
  width: max-content;
}

.marquee__chip {
  margin-right: 14px;
  flex-shrink: 0;
  display: grid;
  place-items: center;
  height: 30px;
  padding: 0 12px;
  border-radius: 12px;
  background: rgba(255, 247, 230, 0.1);
  color: #fff7e6;
  font-weight: 700;
  font-size: 12px;
  line-height: 1;
  font-family: inherit;
}

.panel__state {
  position: relative;
  width: 100%;
  min-width: 84px;
  height: 16px;
}

.panel__state-text {
  position: absolute;
  inset: 0;
  width: 100%;
  text-align: center;
  white-space: nowrap;
  font-weight: 700;
  font-size: 12px;
  line-height: 16px;
  font-family: inherit;
  color: rgba(255, 247, 230, 0.7);
}

.panel__toggle {
  display: flex;
  align-items: center;
  gap: 8px;
}

.panel__toggle-track {
  position: relative;
  width: 36px;
  height: 20px;
  border-radius: 999px;
  background: rgba(255, 247, 230, 0.18);
}

.panel__toggle-knob {
  position: absolute;
  top: 2px;
  left: 2px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: #2f6df6;
}

.panel__toggle-label {
  font-weight: 600;
  font-size: 11px;
  line-height: 1;
  font-family: inherit;
  color: rgba(255, 247, 230, 0.68);
}

.panel.is-demo .marquee__track {
  animation: marquee-toggle 2s linear infinite;
}

.panel.is-demo .panel__toggle-knob {
  animation: toggle-knob 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.panel.is-demo .panel__toggle-track {
  animation: toggle-track 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.panel.is-demo .panel__state-text--play {
  animation: state-play 2s steps(1) infinite;
}

.panel.is-demo .panel__state-text--pause {
  animation: state-pause 2s steps(1) infinite;
}

@keyframes marquee-toggle {
  0% {
    transform: translateX(0);
  }
  55% {
    transform: translateX(-30%);
  }
  100% {
    transform: translateX(-30%);
  }
}
@keyframes toggle-knob {
  0%, 50% {
    transform: translateX(0);
  }
  70%, 100% {
    transform: translateX(16px);
  }
}
@keyframes toggle-track {
  0%, 50% {
    background: rgba(255, 247, 230, 0.18);
  }
  70%, 100% {
    background: rgba(47, 109, 246, 0.38);
  }
}
@keyframes state-play {
  0%, 50% {
    opacity: 1;
  }
  60%, 100% {
    opacity: 0;
  }
}
@keyframes state-pause {
  0%, 50% {
    opacity: 0;
  }
  60%, 100% {
    opacity: 1;
  }
}
@media (prefers-reduced-motion: reduce) {
  .marquee__track, .panel__toggle-knob, .panel__toggle-track,
  .panel__state-text--play, .panel__state-text--pause {
    animation: none !important;
  }
  .panel.is-demo .marquee__track {
    transform: translateX(-30%);
  }
  .panel.is-demo .panel__toggle-knob {
    transform: translateX(16px);
  }
  .panel.is-demo .panel__toggle-track {
    background: rgba(47, 109, 246, 0.38);
  }
  .panel.is-demo .panel__state-text--play {
    opacity: 0;
  }
  .panel.is-demo .panel__state-text--pause {
    opacity: 1;
  }
}

import { useState } from "react";
import type { CSSProperties } from "react";
import styles from "./ReducedMotionMarquee.module.scss";

export type ReducedMotionMarqueeProps = {
  items?: string[];
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

export default function ReducedMotionMarquee({
  items = ["공지", "업데이트", "이벤트"],
  duration = 12000,
  easing = "linear",
  color = "#2f6df6",
}: ReducedMotionMarqueeProps) {
  const [reduced, setReduced] = useState(false);
  const vars: Vars = {
    "--duration": `${duration}ms`,
    "--easing": easing,
    "--color": color,
    animationPlayState: reduced ? "paused" : "running",
  } as Vars;

  return (
    <div className={styles.panel}>
      <div className={styles.marquee}>
        <div className={styles.track} style={vars}>
          {items.map((it) => (
            <span key={it} className={styles.chip}>{it}</span>
          ))}
          {items.map((it) => (
            <span key={"dup-" + it} className={styles.chip} aria-hidden="true">{it}</span>
          ))}
        </div>
      </div>
      <span className={styles.state}>{reduced ? "정지됨" : "재생 중"}</span>
      <button type="button" className={styles.toggle} aria-pressed={reduced} onClick={() => setReduced((v) => !v)}>
        <span className={styles.switchTrack} data-on={reduced}><span className={styles.knob} /></span>
        동작 줄이기
      </button>
    </div>
  );
}