03Liquid glass button refraction

<main class="stage">
  <button class="lb-btn lb-focal is-demo" type="button">
    <span class="lb-btn__label">Get started</span>
  </button>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-enter;
$easing: $ease-out;
$color: $subject-cream;

@include stage($stage-orange);

.lb-btn {
  position: relative;
  overflow: hidden;
  box-sizing: border-box;
  padding: $sp-3 $sp-8;
  border: 1px solid rgba(255, 255, 255, .4);
  border-radius: $r-control;
  background: rgba(255, 255, 255, .16);
  backdrop-filter: blur(12px) saturate(160%);
  -webkit-backdrop-filter: blur(12px) saturate(160%);
  box-shadow: $shadow-press;
  color: $subject-ink;
  font: 700 14px/1 -apple-system, "Segoe UI", sans-serif;
  cursor: pointer;
}
.lb-btn__label { position: relative; z-index: 1; }

// 굴절 하이라이트 — 좁은 빛줄기 레이어. transform 만 움직인다 (top/left 는 고정)
.lb-btn::before {
  content: "";
  position: absolute;
  top: -20%; left: -40%;
  width: 40%; height: 140%;
  background: linear-gradient(100deg, transparent, $color, transparent);
  opacity: .8;
  transform: translateX(-40%) skewX(-18deg);
  transition: transform $duration $easing;
}

// 실사용: 진짜 마우스 호버로 빛줄기가 한 번 지나간다
.lb-focal:hover::before { transform: translateX(340%) skewX(-18deg); }

// 데모 루프: is-demo 는 같은 이동을 keyframes 로 반복
@keyframes lb-sweep {
  0%, 20%  { transform: translateX(-40%) skewX(-18deg); }
  60%, 100% { transform: translateX(340%) skewX(-18deg); }
}
.lb-btn.is-demo::before { animation: lb-sweep $dur-loop $easing infinite; }

@media (prefers-reduced-motion: reduce) {
  .lb-focal:hover::before,
  .lb-btn.is-demo::before { animation: none !important; transition: none !important; transform: translateX(-40%) skewX(-18deg) !important; }
}

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);
}

.lb-btn {
  position: relative;
  overflow: hidden;
  box-sizing: border-box;
  padding: 12px 32px;
  border: 1px solid rgba(255, 255, 255, 0.4);
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.16);
  backdrop-filter: blur(12px) saturate(160%);
  -webkit-backdrop-filter: blur(12px) saturate(160%);
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  color: #17141a;
  font: 700 14px/1 -apple-system, "Segoe UI", sans-serif;
  cursor: pointer;
}

.lb-btn__label {
  position: relative;
  z-index: 1;
}

.lb-btn::before {
  content: "";
  position: absolute;
  top: -20%;
  left: -40%;
  width: 40%;
  height: 140%;
  background: linear-gradient(100deg, transparent, #fff7e6, transparent);
  opacity: 0.8;
  transform: translateX(-40%) skewX(-18deg);
  transition: transform 600ms ease-out;
}

.lb-focal:hover::before {
  transform: translateX(340%) skewX(-18deg);
}

@keyframes lb-sweep {
  0%, 20% {
    transform: translateX(-40%) skewX(-18deg);
  }
  60%, 100% {
    transform: translateX(340%) skewX(-18deg);
  }
}
.lb-btn.is-demo::before {
  animation: lb-sweep 2s ease-out infinite;
}

@media (prefers-reduced-motion: reduce) {
  .lb-focal:hover::before,
  .lb-btn.is-demo::before {
    animation: none !important;
    transition: none !important;
    transform: translateX(-40%) skewX(-18deg) !important;
  }
}

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

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

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

export default function LiquidGlassButton({
  duration = "600ms",
  easing = "ease-out",
  color = "#fff7e6",
}: LiquidGlassButtonProps) {
  const style: Vars = {
    "--duration": duration,
    "--easing": easing,
    "--color": color,
  };
  return (
    <button className={styles.btn} style={style} type="button">
      <span className={styles.label}>Get started</span>
    </button>
  );
}