05Nút trượt mũi tên

<main class="stage is-demo">
  <button class="btn" type="button">
    <span class="btn__track">
      <span class="btn__cell">Xem thêm</span>
      <span class="btn__cell">
        Xem thêm
        <svg class="btn__arrow" viewBox="0 0 256 256" aria-hidden="true" focusable="false">
          <g fill="currentColor"><path d="m216 128l-72 72V56Z" opacity=".2"/><path d="m221.66 122.34l-72-72A8 8 0 0 0 136 56v64H40a8 8 0 0 0 0 16h96v64a8 8 0 0 0 13.66 5.66l72-72a8 8 0 0 0 0-11.32M152 180.69V75.31L204.69 128Z"/></g>
        </svg>
      </span>
    </span>
  </button>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;      // 2s — 슬라이드 한 주기
$easing: $ease-spring;
$color: $stage-orange;     // 화살표 포인트색

@include stage($stage-ink);

.btn {
  box-sizing: border-box;
  position: relative;
  width: 240px;
  height: 64px;
  border: none;
  border-radius: $r-pill;
  background: $subject-cream;
  color: $subject-ink;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 700;
  font-size: 17px;
  cursor: pointer;
  overflow: hidden;          // 두 칸 중 보이는 칸은 늘 하나
}

// 두 칸 트랙 — transform 으로 좌우 이동만 (레이아웃 고정)
.btn__track {
  display: flex;
  width: 200%;
  height: 100%;
  transition: transform $dur-base $easing;
}
.btn__cell {
  box-sizing: border-box;
  flex: 0 0 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: $sp-2;
  white-space: nowrap;
}

.btn__arrow {
  width: 20px;
  height: 20px;
  color: $color;   // Phosphor duotone: g fill="currentColor" 가 이 값을 물려받는다
}

// 실사용: 올리면 두 번째 칸(라벨+화살표)이 오른쪽에서 들어온다
.btn:hover .btn__track { transform: translateX(-50%); }

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

// 격자 미리보기: 밀었다 되돌아오는 루프
.stage.is-demo .btn__track { animation: slide-in $duration $easing infinite; }

@keyframes slide-in {
  0%, 18%   { transform: translateX(0); }
  55%, 72%  { transform: translateX(-50%); }
  88%       { transform: translateX(-4%); }   // 살짝 되튕김
  100%      { transform: translateX(0); }
}

@media (prefers-reduced-motion: reduce) {
  .stage.is-demo .btn__track { animation: none; transform: translateX(-50%); }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.btn {
  box-sizing: border-box;
  position: relative;
  width: 240px;
  height: 64px;
  border: none;
  border-radius: 999px;
  background: #fff7e6;
  color: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 700;
  font-size: 17px;
  cursor: pointer;
  overflow: hidden;
}

.btn__track {
  display: flex;
  width: 200%;
  height: 100%;
  transition: transform 300ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.btn__cell {
  box-sizing: border-box;
  flex: 0 0 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  white-space: nowrap;
}

.btn__arrow {
  width: 20px;
  height: 20px;
  color: #ff4d1f;
}

.btn:hover .btn__track {
  transform: translateX(-50%);
}

.btn:focus-visible {
  outline: 3px solid #ffd23f;
  outline-offset: 4px;
}

.stage.is-demo .btn__track {
  animation: slide-in 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@keyframes slide-in {
  0%, 18% {
    transform: translateX(0);
  }
  55%, 72% {
    transform: translateX(-50%);
  }
  88% {
    transform: translateX(-4%);
  }
  100% {
    transform: translateX(0);
  }
}
@media (prefers-reduced-motion: reduce) {
  .stage.is-demo .btn__track {
    animation: none;
    transform: translateX(-50%);
  }
}

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

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

export default function IconSlideButton({
  duration = 300,
  easing = "cubic-bezier(.2, .8, .2, 1)",
  color = "#ff4d1f",
  label = "소개 더보기",
}: IconSlideButtonProps) {
  const vars: CSSProperties = { "--duration": `${duration}ms`, "--easing": easing, "--color": color } as CSSProperties;
  return (
    <button className={styles.btn} style={vars} type="button">
      <span className={styles.track}>
        <span className={styles.cell}>{label}</span>
        <span className={styles.cell}>
          {label}
          <svg className={styles.arrow} viewBox="0 0 256 256" aria-hidden="true" focusable="false">
            <g fill="currentColor"><path d="m216 128l-72 72V56Z" opacity=".2" /><path d="m221.66 122.34l-72-72A8 8 0 0 0 136 56v64H40a8 8 0 0 0 0 16h96v64a8 8 0 0 0 13.66 5.66l72-72a8 8 0 0 0 0-11.32M152 180.69V75.31L204.69 128Z" /></g>
          </svg>
        </span>
      </span>
    </button>
  );
}