03Lan tỏa hình tròn (View Transitions)

<main class="stage">
  <div class="panel">
    <p class="panel__title">Landing</p>
    <p class="panel__line"></p>
    <span class="wipe"></span>
    <span class="origin"></span>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────
$duration: $dur-enter;
$easing: $ease-pop;
$color: $stage-ink;

// ── 데모 무대 ───────────────────────────────
@include stage($stage-orange);

.panel {
  position: relative; overflow: hidden;
  width: clamp(200px, 70vw, 260px); height: clamp(120px, 42vw, 150px);
  border-radius: $r-card; box-shadow: $shadow-raised;
  background: $subject-cream; color: $subject-ink;
  box-sizing: border-box; padding: clamp(12px, 5vw, 18px); text-align: left;
}
.panel__title { position: relative; z-index: 1; margin: 0 0 6px; font-weight: 700; font-size: clamp(12px, 3.6vw, 15px); line-height: 1.3; font-family: inherit; }
.panel__line { position: relative; z-index: 1; margin: 0; width: 55%; height: 8px; border-radius: 4px; background: currentColor; opacity: .25; }

// 클릭 지점(우상단 토글 자리)에서 원이 퍼져 화면을 다크모드로 덮는다. transform: scale 하나로.
.wipe {
  position: absolute; z-index: 0; top: -60px; right: -60px;
  width: 320px; height: 320px; border-radius: 50%;
  background: $color; transform-origin: 78% 22%; // 규칙8: 클릭 지점서 퍼짐
  transform: scale(0); animation: wipe-scale $dur-loop $easing infinite;
}
.origin {
  position: absolute; z-index: 2; top: clamp(8px, 3vw, 12px); right: clamp(8px, 3vw, 12px);
  width: 14px; height: 14px; border-radius: 50%; background: $stage-yellow;
  animation: origin-pulse $dur-loop $easing infinite;
}

@keyframes wipe-scale {
  0%, 10%  { transform: scale(0); }
  45%, 55% { transform: scale(1); }
  90%, 100% { transform: scale(0); }
}
@keyframes origin-pulse {
  0%, 10%  { opacity: 1; transform: scale(1); }
  45%, 55% { opacity: .4; transform: scale(1.3); }
  90%, 100% { opacity: 1; transform: scale(1); }
}

// ── 접근성: 움직임 줄이기 설정이면 원이 퍼지지 않는다 ──────────
@media (prefers-reduced-motion: reduce) {
  .wipe, .origin { animation: none !important; transform: scale(0); }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.panel {
  position: relative;
  overflow: hidden;
  width: clamp(200px, 70vw, 260px);
  height: clamp(120px, 42vw, 150px);
  border-radius: 16px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  background: #fff7e6;
  color: #17141a;
  box-sizing: border-box;
  padding: clamp(12px, 5vw, 18px);
  text-align: left;
}

.panel__title {
  position: relative;
  z-index: 1;
  margin: 0 0 6px;
  font-weight: 700;
  font-size: clamp(12px, 3.6vw, 15px);
  line-height: 1.3;
  font-family: inherit;
}

.panel__line {
  position: relative;
  z-index: 1;
  margin: 0;
  width: 55%;
  height: 8px;
  border-radius: 4px;
  background: currentColor;
  opacity: 0.25;
}

.wipe {
  position: absolute;
  z-index: 0;
  top: -60px;
  right: -60px;
  width: 320px;
  height: 320px;
  border-radius: 50%;
  background: #17141a;
  transform-origin: 78% 22%;
  transform: scale(0);
  animation: wipe-scale 2s cubic-bezier(0.2, 1.4, 0.4, 1) infinite;
}

.origin {
  position: absolute;
  z-index: 2;
  top: clamp(8px, 3vw, 12px);
  right: clamp(8px, 3vw, 12px);
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: #ffd23f;
  animation: origin-pulse 2s cubic-bezier(0.2, 1.4, 0.4, 1) infinite;
}

@keyframes wipe-scale {
  0%, 10% {
    transform: scale(0);
  }
  45%, 55% {
    transform: scale(1);
  }
  90%, 100% {
    transform: scale(0);
  }
}
@keyframes origin-pulse {
  0%, 10% {
    opacity: 1;
    transform: scale(1);
  }
  45%, 55% {
    opacity: 0.4;
    transform: scale(1.3);
  }
  90%, 100% {
    opacity: 1;
    transform: scale(1);
  }
}
@media (prefers-reduced-motion: reduce) {
  .wipe, .origin {
    animation: none !important;
    transform: scale(0);
  }
}

import type { CSSProperties, ReactNode } from "react";
import styles from "./CircleExpandToggle.module.scss";

export type CircleExpandToggleProps = {
  dark: boolean;
  onToggle?: () => void;
  /** 원이 다 퍼지는 시간 (기본 600ms) */
  duration?: number;
  easing?: string;
  /** 다크모드로 덮는 원의 색 */
  color?: string;
  children?: ReactNode;
  className?: string;
};

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

export default function CircleExpandToggle({
  dark,
  onToggle,
  duration = 600,
  easing = "cubic-bezier(.2,1.4,.4,1)",
  color = "#17141a",
  children,
  className = "",
}: CircleExpandToggleProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return (
    <div className={`${styles.panel} ${className}`} style={vars} data-dark={dark}>
      <div className={styles.content}>{children}</div>
      <span className={styles.wipe} />
      <button type="button" className={styles.origin} aria-label="다크모드 전환" onClick={onToggle} />
    </div>
  );
}