083D push-down button

<main class="stage is-demo">
  <button class="btn" type="button">Start game</button>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;     // 2s — 눌림 한 주기
$easing: $ease-out;
$color: #e7cfd8;          // 캔디 핑크
$depth: 8px;              // 두께 — 눌림 거리와 같다

@include stage($stage-paper);

.btn {
  box-sizing: border-box;
  width: 240px;
  height: 64px;
  border: none;
  border-radius: $r-control;
  background: $color;
  color: $subject-ink;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 800;
  font-size: 18px;
  cursor: pointer;
  // 두께(box-shadow) + 받침 그림자 — 누르면 둘 다 사라진다
  box-shadow: 0 $depth 0 darken($color, 22%),
              0 #{$depth + 6px} #{$sp-3} rgba(23, 20, 26, .22);
  transition: transform $dur-quick $easing, box-shadow $dur-quick $easing;
}

// 실사용: 누르는 동안 꾹 들어간다
.btn:active {
  transform: translateY($depth);
  box-shadow: 0 0 0 darken($color, 22%),
              0 2px 4px rgba(23, 20, 26, .22);
}

.btn:focus-visible { outline: 3px solid $subject-blue; outline-offset: 4px; }

// 격자 미리보기: 눌림 → 유지 → 튕겨 복귀 루프
.stage.is-demo .btn { animation: press $duration $easing infinite; }

@keyframes press {
  0%, 20% {
    transform: translateY(0);
    box-shadow: 0 $depth 0 darken($color, 22%),
                0 #{$depth + 6px} #{$sp-3} rgba(23, 20, 26, .22);
  }
  35%, 55% {
    transform: translateY($depth);
    box-shadow: 0 0 0 darken($color, 22%),
                0 2px 4px rgba(23, 20, 26, .22);
  }
  70% {
    transform: translateY(-3px);
    box-shadow: 0 #{$depth + 3px} 0 darken($color, 22%),
                0 #{$depth + 9px} #{$sp-3} rgba(23, 20, 26, .22);
  }
  85%, 100% {
    transform: translateY(0);
    box-shadow: 0 $depth 0 darken($color, 22%),
                0 #{$depth + 6px} #{$sp-3} rgba(23, 20, 26, .22);
  }
}

@media (prefers-reduced-motion: reduce) {
  .stage.is-demo .btn { animation: none; }
}

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);
}

.btn {
  box-sizing: border-box;
  width: 240px;
  height: 64px;
  border: none;
  border-radius: 12px;
  background: #e7cfd8;
  color: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 800;
  font-size: 18px;
  cursor: pointer;
  box-shadow: 0 8px 0 rgb(75.9215686275%, 51.8431372549%, 60.8725490196%), 0 14px 12px rgba(23, 20, 26, 0.22);
  transition: transform 220ms ease-out, box-shadow 220ms ease-out;
}

.btn:active {
  transform: translateY(8px);
  box-shadow: 0 0 0 rgb(75.9215686275%, 51.8431372549%, 60.8725490196%), 0 2px 4px rgba(23, 20, 26, 0.22);
}

.btn:focus-visible {
  outline: 3px solid #2f6df6;
  outline-offset: 4px;
}

.stage.is-demo .btn {
  animation: press 2s ease-out infinite;
}

@keyframes press {
  0%, 20% {
    transform: translateY(0);
    box-shadow: 0 8px 0 rgb(75.9215686275%, 51.8431372549%, 60.8725490196%), 0 14px 12px rgba(23, 20, 26, 0.22);
  }
  35%, 55% {
    transform: translateY(8px);
    box-shadow: 0 0 0 rgb(75.9215686275%, 51.8431372549%, 60.8725490196%), 0 2px 4px rgba(23, 20, 26, 0.22);
  }
  70% {
    transform: translateY(-3px);
    box-shadow: 0 11px 0 rgb(75.9215686275%, 51.8431372549%, 60.8725490196%), 0 17px 12px rgba(23, 20, 26, 0.22);
  }
  85%, 100% {
    transform: translateY(0);
    box-shadow: 0 8px 0 rgb(75.9215686275%, 51.8431372549%, 60.8725490196%), 0 14px 12px rgba(23, 20, 26, 0.22);
  }
}
@media (prefers-reduced-motion: reduce) {
  .stage.is-demo .btn {
    animation: none;
  }
}

import type { CSSProperties } from "react";
import styles from "./Push3dButton.module.scss";

export type Push3dButtonProps = {
  duration?: number;
  easing?: string;
  color?: string;
  label?: string;
};

export default function Push3dButton({
  duration = 220,
  easing = "ease-out",
  color = "#ff7fae",
  label = "게임 시작",
}: Push3dButtonProps) {
  const vars: CSSProperties = {
    "--duration": `${duration}ms`,
    "--easing": easing,
    "--color": color,
    "--depth": "8px",
  } as CSSProperties;
  return (
    <button className={styles.btn} style={vars} type="button">{label}</button>
  );
}