02Sticker corner peel + holographic sweep

<main class="stage">
  <div class="sticker is-demo" tabindex="0">
    <span class="sticker__peel" aria-hidden="true"></span>
    <span class="sticker__shine" aria-hidden="true"></span>
    <span class="sticker__flag">NEW</span>
  </div>
</main>

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

$duration: $dur-base;                                  // 모서리가 더 들리는 시간
$easing: $ease-out;
$color: $subject-cream;                                // 스티커 바탕색

@include stage($stage-yellow);

.sticker {
  position: relative;
  width: min(150px, 48vw);
  aspect-ratio: 1;
  border-radius: $r-card;
  background: $color;
  box-shadow: $shadow-press;
  overflow: hidden;
  outline: none;
  cursor: pointer;
}
.sticker__peel {
  position: absolute; top: 0; right: 0;
  width: 40px; height: 40px;
  background: linear-gradient(135deg, rgba($stage-ink, .08) 50%, $stage-paper 50%);
  clip-path: polygon(100% 0, 0 0, 100% 100%);
  transform-origin: 100% 0; // 규칙8: 스티커 접힌 코너 경첩
  box-shadow: -6px 6px 12px rgba($stage-ink, .28);
}
.sticker__shine {
  position: absolute; inset: 0;
  background: repeating-linear-gradient(115deg,
    transparent 0 10%, #dcb9d1 10% 12%, #b9d9dc 12% 14%, #c8dcb9 14% 16%, #dcdab9 16% 18%, transparent 18% 30%);
  background-size: 260% 260%;
  background-position: -60% -60%;
  mix-blend-mode: multiply;
  opacity: 0;
}
.sticker__flag {
  position: absolute; left: $sp-3; bottom: $sp-3;
  font-weight: 800; font-size: 12px; letter-spacing: .04em; color: $stage-ink; font-family: inherit;
}

.sticker:hover .sticker__peel,
.sticker:focus-visible .sticker__peel { transform: rotate(-16deg) translate(6px, -6px); }
.sticker:hover .sticker__shine,
.sticker:focus-visible .sticker__shine { opacity: .9; background-position: 60% 60%; transition: opacity $duration $easing, background-position $duration $easing; }

.sticker.is-demo .sticker__peel { animation: peel-loop $dur-loop $easing infinite; }
.sticker.is-demo .sticker__shine { animation: sweep-loop $dur-loop $easing infinite; }

@keyframes peel-loop {
  0%, 10%   { transform: rotate(-6deg) translate(2px, -2px); }
  40%       { transform: rotate(-18deg) translate(7px, -7px); }
  70%       { transform: rotate(-13deg) translate(5px, -5px); }
  90%, 100% { transform: rotate(-6deg) translate(2px, -2px); }
}
@keyframes sweep-loop {
  0%, 10%   { opacity: 0;  background-position: -60% -60%; }
  40%       { opacity: .9; background-position: 20% 20%; }
  70%       { opacity: .9; background-position: 90% 90%; }
  90%, 100% { opacity: 0;  background-position: 150% 150%; }
}

@media (prefers-reduced-motion: reduce) {
  .sticker__peel { transform: rotate(-12deg) translate(4px, -4px); }
  .sticker__shine { opacity: .5; background-position: 40% 40%; }
  .sticker.is-demo .sticker__peel,
  .sticker.is-demo .sticker__shine { animation: none; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.sticker {
  position: relative;
  width: min(150px, 48vw);
  aspect-ratio: 1;
  border-radius: 16px;
  background: #fff7e6;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  overflow: hidden;
  outline: none;
  cursor: pointer;
}

.sticker__peel {
  position: absolute;
  top: 0;
  right: 0;
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, rgba(23, 20, 26, 0.08) 50%, #ffffff 50%);
  clip-path: polygon(100% 0, 0 0, 100% 100%);
  transform-origin: 100% 0;
  box-shadow: -6px 6px 12px rgba(23, 20, 26, 0.28);
}

.sticker__shine {
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(115deg, transparent 0 10%, #dcb9d1 10% 12%, #b9d9dc 12% 14%, #c8dcb9 14% 16%, #dcdab9 16% 18%, transparent 18% 30%);
  background-size: 260% 260%;
  background-position: -60% -60%;
  mix-blend-mode: multiply;
  opacity: 0;
}

.sticker__flag {
  position: absolute;
  left: 12px;
  bottom: 12px;
  font-weight: 800;
  font-size: 12px;
  letter-spacing: 0.04em;
  color: #17141a;
  font-family: inherit;
}

.sticker:hover .sticker__peel,
.sticker:focus-visible .sticker__peel {
  transform: rotate(-16deg) translate(6px, -6px);
}

.sticker:hover .sticker__shine,
.sticker:focus-visible .sticker__shine {
  opacity: 0.9;
  background-position: 60% 60%;
  transition: opacity 300ms ease-out, background-position 300ms ease-out;
}

.sticker.is-demo .sticker__peel {
  animation: peel-loop 2s ease-out infinite;
}

.sticker.is-demo .sticker__shine {
  animation: sweep-loop 2s ease-out infinite;
}

@keyframes peel-loop {
  0%, 10% {
    transform: rotate(-6deg) translate(2px, -2px);
  }
  40% {
    transform: rotate(-18deg) translate(7px, -7px);
  }
  70% {
    transform: rotate(-13deg) translate(5px, -5px);
  }
  90%, 100% {
    transform: rotate(-6deg) translate(2px, -2px);
  }
}
@keyframes sweep-loop {
  0%, 10% {
    opacity: 0;
    background-position: -60% -60%;
  }
  40% {
    opacity: 0.9;
    background-position: 20% 20%;
  }
  70% {
    opacity: 0.9;
    background-position: 90% 90%;
  }
  90%, 100% {
    opacity: 0;
    background-position: 150% 150%;
  }
}
@media (prefers-reduced-motion: reduce) {
  .sticker__peel {
    transform: rotate(-12deg) translate(4px, -4px);
  }
  .sticker__shine {
    opacity: 0.5;
    background-position: 40% 40%;
  }
  .sticker.is-demo .sticker__peel,
  .sticker.is-demo .sticker__shine {
    animation: none;
  }
}

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

export type StickerPeelShineProps = {
  flag: string;
  /** 모서리가 더 들리는 시간 (기본 300ms) */
  duration?: number;
  easing?: string;
  /** 스티커 바탕색 */
  color?: string;
};

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

export default function StickerPeelShine({
  flag,
  duration = 300,
  easing = "ease-out",
  color = "#fff7e6",
}: StickerPeelShineProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return (
    <div className={styles.sticker} style={vars} tabIndex={0}>
      <span className={styles.peel} aria-hidden="true" />
      <span className={styles.shine} aria-hidden="true" />
      <span className={styles.flag}>{flag}</span>
    </div>
  );
}