05Strikethrough draw-on

<main class="stage">
  <p class="price">
    <span class="price__old">₩39,000<span class="price__strike" aria-hidden="true"></span></span>
    <span class="price__new">₩29,000</span>
  </p>
</main>

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

// ── 변수 3개 ─────────────────────────────
$duration: 500ms;
$easing: $ease-spring;
$color: $error;                // 취소선 색

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

.price {
  display: flex;
  align-items: baseline;
  gap: $sp-3;
  margin: 0;
  font-weight: 700;
  font-size: clamp(18px, 5vw, 24px);
  line-height: 1;
  font-family: inherit;
}

.price__old {
  position: relative;
  color: color-mix(in srgb, $stage-ink 55%, transparent);
  font-weight: 500;
}

// 글자 중간 높이에 놓인 가로선을 왼쪽부터 그어 취소선을 만든다
.price__strike {
  position: absolute;
  left: -2%;
  right: -2%;
  top: 52%;
  height: 2px;
  background: $color;
  transform: scaleX(0);
  transform-origin: left center; // 규칙8: 취소선 왼쪽에서 그어짐
  animation: strike $duration $easing infinite, strike-thick $duration ease-in-out infinite;
}

.price__new {
  color: $stage-ink;
}

@keyframes strike {
  0%   { transform: scaleX(0); }
  30%  { transform: scaleX(1); }
  80%  { transform: scaleX(1); }
  100% { transform: scaleX(0); }
}

// 한 겹: 취소선 두께 요동 — height 변조(transform 아님)라 strike 의 scaleX 와 병렬 가능.
// rotate 진동은 transform 충돌이라 생략하고 height 로만 펜 압력을 표현한다
@keyframes strike-thick {
  0%   { height: 2px; }
  25%  { height: 3px; }
  50%  { height: 1.5px; }
  75%  { height: 2.5px; }
  100% { height: 2px; }
}

@media (prefers-reduced-motion: reduce) {
  .price__strike { animation: none; transform: scaleX(1); }
}

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);
}

.price {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin: 0;
  font-weight: 700;
  font-size: clamp(18px, 5vw, 24px);
  line-height: 1;
  font-family: inherit;
}

.price__old {
  position: relative;
  color: color-mix(in srgb, #17141a 55%, transparent);
  font-weight: 500;
}

.price__strike {
  position: absolute;
  left: -2%;
  right: -2%;
  top: 52%;
  height: 2px;
  background: #c2361a;
  transform: scaleX(0);
  transform-origin: left center;
  animation: strike 500ms cubic-bezier(0.2, 0.8, 0.2, 1) infinite, strike-thick 500ms ease-in-out infinite;
}

.price__new {
  color: #17141a;
}

@keyframes strike {
  0% {
    transform: scaleX(0);
  }
  30% {
    transform: scaleX(1);
  }
  80% {
    transform: scaleX(1);
  }
  100% {
    transform: scaleX(0);
  }
}
@keyframes strike-thick {
  0% {
    height: 2px;
  }
  25% {
    height: 3px;
  }
  50% {
    height: 1.5px;
  }
  75% {
    height: 2.5px;
  }
  100% {
    height: 2px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .price__strike {
    animation: none;
    transform: scaleX(1);
  }
}

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

export type StrikeDrawProps = {
  /** 취소선이 그어지는 이전 가격 */
  oldPrice: string;
  /** 강조되는 새 가격 */
  newPrice: string;
  /** 선이 그어지는 시간 (기본 500ms) */
  duration?: number;
  easing?: string;
  /** 취소선 색 */
  color?: string;
};

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

export default function StrikeDraw({
  oldPrice,
  newPrice,
  duration = 500,
  easing = "cubic-bezier(.2,1.4,.4,1)",
  color = "#c2361a",
}: StrikeDrawProps) {
  const vars: Vars = {
    "--duration": `${duration}ms`,
    "--easing": easing,
    "--color": color,
  };
  return (
    <p className={styles.price} style={vars}>
      <span className={styles.old}>
        {oldPrice}
        <span className={styles.strike} aria-hidden="true" />
      </span>
      <span className={styles.new}>{newPrice}</span>
    </p>
  );
}