09Outline fallback for reduced motion

<main class="stage">
  <div class="rm is-demo">
    <label class="rm__label" for="rm-msg">Message</label>
    <div class="rm__field">
      <textarea class="rm__textarea" id="rm-msg" rows="2"></textarea>
      <span class="rm__ring" aria-hidden="true"></span>
    </div>
    <p class="rm__msg">Must be at least 10 characters</p>
  </div>
</main>

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

$duration: 500ms;                                 // 평소 흔들림 한 번의 길이
$easing: $ease-out;
$color: $error;

@include stage($stage-ink);

.rm { width: min(260px, 86vw); display: flex; flex-direction: column; gap: $sp-2; }
.rm__label { font-weight: 600; font-size: 12px; line-height: 1; font-family: inherit; color: $subject-cream; }
.rm__field { position: relative; }
.rm__textarea {
  box-sizing: border-box;
  width: 100%;
  resize: none;
  padding: $sp-2 $sp-3;
  border-radius: $r-sm;
  border: 2px solid $color;
  background: rgba(255, 255, 255, .06);
  color: $subject-cream;
  font-weight: 400;
  font-size: 13px;
  line-height: 1.4;
  font-family: inherit;
}
.rm__ring {
  position: absolute;
  inset: -$sp-1;
  border: 2px solid $color;
  border-radius: $r-sm;
  opacity: 0;
  pointer-events: none;
}
.rm__msg { margin: 0; color: $error-soft; font-weight: 500; font-size: 11px; line-height: 1.3; font-family: inherit; }

// 평소: translateX 로 흔든다
@keyframes rm-shake {
  0%, 22%, 100% { transform: translateX(0); }
  2%  { transform: translateX(-6px); }
  4%  { transform: translateX(6px); }
  6%  { transform: translateX(-6px); }
  8%  { transform: translateX(6px); }
  10% { transform: translateX(-4px); }
  12% { transform: translateX(4px); }
  14% { transform: translateX(-2px); }
  16% { transform: translateX(2px); }
}
.rm__textarea.rm--invalid { animation: rm-shake $duration $easing; }
.rm.is-demo .rm__textarea { animation: rm-shake $duration $easing infinite; }

// 모션 축소: 흔들림 대신 opacity 로 링만 두 번 깜빡인다 — 움직임은 없지만 오류는 여전히 보인다
@keyframes rm-ring-pulse {
  0%, 100% { opacity: 0; }
  25% { opacity: 1; }
  50% { opacity: 0; }
  75% { opacity: 1; }
}
@media (prefers-reduced-motion: reduce) {
  .rm__textarea.rm--invalid,
  .rm.is-demo .rm__textarea { animation: none !important; }
  .rm__ring.rm--invalid { animation: rm-ring-pulse $dur-loop ease-in-out; }
  .rm.is-demo .rm__ring { animation: rm-ring-pulse $dur-loop ease-in-out infinite; }
}

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);
}

.rm {
  width: min(260px, 86vw);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.rm__label {
  font-weight: 600;
  font-size: 12px;
  line-height: 1;
  font-family: inherit;
  color: #fff7e6;
}

.rm__field {
  position: relative;
}

.rm__textarea {
  box-sizing: border-box;
  width: 100%;
  resize: none;
  padding: 8px 12px;
  border-radius: 8px;
  border: 2px solid #c2361a;
  background: rgba(255, 255, 255, 0.06);
  color: #fff7e6;
  font-weight: 400;
  font-size: 13px;
  line-height: 1.4;
  font-family: inherit;
}

.rm__ring {
  position: absolute;
  inset: -4px;
  border: 2px solid #c2361a;
  border-radius: 8px;
  opacity: 0;
  pointer-events: none;
}

.rm__msg {
  margin: 0;
  color: #ffe0d8;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.3;
  font-family: inherit;
}

@keyframes rm-shake {
  0%, 22%, 100% {
    transform: translateX(0);
  }
  2% {
    transform: translateX(-6px);
  }
  4% {
    transform: translateX(6px);
  }
  6% {
    transform: translateX(-6px);
  }
  8% {
    transform: translateX(6px);
  }
  10% {
    transform: translateX(-4px);
  }
  12% {
    transform: translateX(4px);
  }
  14% {
    transform: translateX(-2px);
  }
  16% {
    transform: translateX(2px);
  }
}
.rm__textarea.rm--invalid {
  animation: rm-shake 500ms ease-out;
}

.rm.is-demo .rm__textarea {
  animation: rm-shake 500ms ease-out infinite;
}

@keyframes rm-ring-pulse {
  0%, 100% {
    opacity: 0;
  }
  25% {
    opacity: 1;
  }
  50% {
    opacity: 0;
  }
  75% {
    opacity: 1;
  }
}
@media (prefers-reduced-motion: reduce) {
  .rm__textarea.rm--invalid,
  .rm.is-demo .rm__textarea {
    animation: none !important;
  }
  .rm__ring.rm--invalid {
    animation: rm-ring-pulse 2s ease-in-out;
  }
  .rm.is-demo .rm__ring {
    animation: rm-ring-pulse 2s ease-in-out infinite;
  }
}

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

export type ReducedMotionOutlineProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

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

export default function ReducedMotionOutline({ duration = 500, easing = "ease-out", color = "#c2361a" }: ReducedMotionOutlineProps) {
  const [run, setRun] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  return (
    <div className={styles.rm} style={vars}>
      <label className={styles.label} htmlFor="rm-msg">문의 내용</label>
      <div className={styles.field}>
        <textarea key={run} id="rm-msg" rows={2} className={`${styles.textarea} ${styles.invalid}`} onFocus={() => setRun((n) => n + 1)} />
        <span key={`ring-${run}`} className={`${styles.ring} ${styles.invalid}`} aria-hidden="true" />
      </div>
      <p className={styles.msg}>10자 이상 입력해야 합니다</p>
    </div>
  );
}