08Send-to-stop button morph

<main class="stage">
  <button class="sm-btn is-demo" type="button" aria-label="Send message">
    <svg class="sm-icon sm-icon--send" viewBox="0 0 24 24"><path d="M3 11l18-8-8 18-2-8-8-2z"/></svg>
    <span class="sm-icon sm-icon--stop"></span>
  </button>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;
$easing: $ease-spring;
$color: $subject-blue;

@include stage($stage-paper);

.sm-btn {
  display: grid;
  place-items: center;
  width: $sp-12;
  height: $sp-12;
  border-radius: $r-pill;
  border: none;
  padding: 0;
  background: $color;
  box-shadow: $shadow-press;
}

.sm-icon {
  grid-column: 1;
  grid-row: 1;
}
.sm-icon--send {
  width: $sp-5;
  height: $sp-5;
  path { fill: $subject-cream; }
}
.sm-icon--stop {
  width: $sp-4;
  height: $sp-4;
  border-radius: $r-xs;
  background: $subject-cream;
  opacity: 0;
  transform: scale(.5);
}

// 실사용: 전송을 누르면 한 번만 재생하고 정지 상태로 멈춘다. 데모는 오가며 반복 재생한다
@keyframes sm-send {
  0%, 12%  { opacity: 1; transform: scale(1); }
  30%, 62% { opacity: 0; transform: scale(.5); }
  80%, 100% { opacity: 1; transform: scale(1); }
}
@keyframes sm-stop {
  0%, 12%  { opacity: 0; transform: scale(.5); }
  30%, 62% { opacity: 1; transform: scale(1); }
  80%, 100% { opacity: 0; transform: scale(.5); }
}

.sm-btn.is-demo .sm-icon--send { animation: sm-send $duration $easing infinite; }
.sm-btn.is-demo .sm-icon--stop { animation: sm-stop $duration $easing infinite; }

@media (prefers-reduced-motion: reduce) {
  .sm-btn.is-demo .sm-icon--send {
    animation: none !important; opacity: 1 !important; transform: scale(1) !important;
  }
  .sm-btn.is-demo .sm-icon--stop {
    animation: none !important; opacity: 0 !important; transform: scale(.5) !important;
  }
}

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

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

.sm-btn {
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  border-radius: 999px;
  border: none;
  padding: 0;
  background: #2f6df6;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
}

.sm-icon {
  grid-column: 1;
  grid-row: 1;
}

.sm-icon--send {
  width: 20px;
  height: 20px;
}
.sm-icon--send path {
  fill: #fff7e6;
}

.sm-icon--stop {
  width: 16px;
  height: 16px;
  border-radius: 4px;
  background: #fff7e6;
  opacity: 0;
  transform: scale(0.5);
}

@keyframes sm-send {
  0%, 12% {
    opacity: 1;
    transform: scale(1);
  }
  30%, 62% {
    opacity: 0;
    transform: scale(0.5);
  }
  80%, 100% {
    opacity: 1;
    transform: scale(1);
  }
}
@keyframes sm-stop {
  0%, 12% {
    opacity: 0;
    transform: scale(0.5);
  }
  30%, 62% {
    opacity: 1;
    transform: scale(1);
  }
  80%, 100% {
    opacity: 0;
    transform: scale(0.5);
  }
}
.sm-btn.is-demo .sm-icon--send {
  animation: sm-send 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.sm-btn.is-demo .sm-icon--stop {
  animation: sm-stop 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@media (prefers-reduced-motion: reduce) {
  .sm-btn.is-demo .sm-icon--send {
    animation: none !important;
    opacity: 1 !important;
    transform: scale(1) !important;
  }
  .sm-btn.is-demo .sm-icon--stop {
    animation: none !important;
    opacity: 0 !important;
    transform: scale(0.5) !important;
  }
}

import { CSSProperties } from "react";
import styles from "./StopButtonMorph.module.scss";

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

export interface StopButtonMorphProps {
  duration?: string;
  easing?: string;
  color?: string;
}

export default function StopButtonMorph({
  duration = "2s",
  easing = "cubic-bezier(.2, .8, .2, 1)",
  color = "#2f6df6",
}: StopButtonMorphProps) {
  const style: Vars = {
    "--duration": duration,
    "--easing": easing,
    "--color": color,
  };
  return (
    <button className={styles.btn} style={style} type="button" aria-label="Send message">
      <svg className={`${styles.icon} ${styles.send}`} viewBox="0 0 24 24">
        <path d="M3 11l18-8-8 18-2-8-8-2z" />
      </svg>
      <span className={`${styles.icon} ${styles.stop}`} />
    </button>
  );
}