09線が伸びるタイムライン

<main class="stage">
  <ul class="timeline is-demo">
    <li class="timeline__step"><span class="timeline__dot"></span>企画</li>
    <li class="timeline__step"><span class="timeline__dot"></span>デザイン</li>
    <li class="timeline__step"><span class="timeline__dot"></span>リリース</li>
    <li class="timeline__line" aria-hidden="true"></li>
  </ul>
</main>

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

// ── 변수 3개. 변형은 이것만 바꾼다 (값은 토큰에서 받는다) ──────
$thickness: 2px;                                 // 선 두께
$color: $subject-cream;                          // 선·점 색 (ink 무대라 cream)
$duration: $dur-enter;                           // 점 하나가 켜지는 시간

// ── 데모 무대 (zip 에서 지워도 된다) ──────────────────────────
@include stage($stage-ink);

// ── 세로 타임라인 ────────────────────────────────────
.timeline {
  position: relative;
  margin: 0;
  padding: 0 0 0 28px;
  list-style: none;
  color: #fff;
  font-weight: 500;
  font-size: 14px;
  line-height: 1;
  font-family: inherit;

  &__step {
    position: relative;
    padding: clamp(4px, 2vw, 6px) 0;
    margin-bottom: clamp(10px, 6vw, 26px);        // 320×200 에서도 세 단계가 들어가게 줄인다
    &:last-of-type { margin-bottom: 0; }
  }

  &__dot {
    position: absolute;
    left: -28px;
    top: 8px;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: $color;                          // 색은 고정. 켜짐/꺼짐은 opacity 로만 표현
    opacity: .28;
    transform: scale(1);

    // ── 실제 사용 코드: 점마다 제 위치에서 뷰포트에 들어오면 켜진다 ──
    @supports (animation-timeline: view()) {
      animation: dot-light $duration ease-out both;
      animation-timeline: view();
      animation-range: entry 30% cover 60%;
    }
    @supports not (animation-timeline: view()) {
      opacity: 1;
    }
  }

  // ── 선: 세로로 그어진다. 실제 사용 코드는 문서 스크롤 진행률에 맞춘다 ──
  &__line {
    position: absolute;
    left: -23px;
    top: 8px;
    width: $thickness;
    height: calc(100% - 16px);
    background: $color;
    transform: scaleY(0);
    transform-origin: top; // 규칙8: 세로선 top에서 차오름

    @supports (animation-timeline: scroll()) {
      animation: line-draw linear both;
      animation-timeline: scroll(root);
      animation-range: 0 200px;
    }
    @supports not (animation-timeline: scroll()) {
      transform: scaleY(1);
    }
  }
}

@keyframes dot-light { from { opacity: .28; transform: scale(1); } to { opacity: 1; transform: scale(1.3); } }
@keyframes line-draw { from { transform: scaleY(0); } to { transform: scaleY(1); } }

// ── 데모(.is-demo): 스크롤 대신 2초 루프로 흉내 (선이 먼저, 점은 순서대로) ──
.timeline.is-demo .timeline__line {
  animation: line-draw-loop $dur-loop ease-in-out infinite;
}
.timeline.is-demo .timeline__step:nth-child(1) .timeline__dot { animation: dot-loop $dur-loop ease-out infinite; animation-delay: 0ms; }
.timeline.is-demo .timeline__step:nth-child(2) .timeline__dot { animation: dot-loop $dur-loop ease-out infinite; animation-delay: 160ms; }
.timeline.is-demo .timeline__step:nth-child(3) .timeline__dot { animation: dot-loop $dur-loop ease-out infinite; animation-delay: 320ms; }

@keyframes line-draw-loop {
  0%   { transform: scaleY(0); }
  60%  { transform: scaleY(1); }
  100% { transform: scaleY(1); }
}
@keyframes dot-loop {
  0%   { opacity: .28; transform: scale(1); }
  15%  { opacity: 1;   transform: scale(1.3); }
  70%  { opacity: 1;   transform: scale(1); }
  85%  { opacity: .28; transform: scale(1); }
  100% { opacity: .28; transform: scale(1); }
}

// ── 접근성: 움직임 줄이기 설정이면 다 켜진 상태로 고정 ────────
@media (prefers-reduced-motion: reduce) {
  .timeline__line, .timeline.is-demo .timeline__line { animation: none !important; transform: scaleY(1); }
  .timeline__dot, .timeline.is-demo .timeline__step .timeline__dot { animation: none !important; opacity: 1; transform: scale(1); }
}

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);
}

.timeline {
  position: relative;
  margin: 0;
  padding: 0 0 0 28px;
  list-style: none;
  color: #fff;
  font-weight: 500;
  font-size: 14px;
  line-height: 1;
  font-family: inherit;
}
.timeline__step {
  position: relative;
  padding: clamp(4px, 2vw, 6px) 0;
  margin-bottom: clamp(10px, 6vw, 26px);
}
.timeline__step:last-of-type {
  margin-bottom: 0;
}
.timeline__dot {
  position: absolute;
  left: -28px;
  top: 8px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #fff7e6;
  opacity: 0.28;
  transform: scale(1);
}
@supports (animation-timeline: view()) {
  .timeline__dot {
    animation: dot-light 600ms ease-out both;
    animation-timeline: view();
    animation-range: entry 30% cover 60%;
  }
}
@supports not (animation-timeline: view()) {
  .timeline__dot {
    opacity: 1;
  }
}
.timeline__line {
  position: absolute;
  left: -23px;
  top: 8px;
  width: 2px;
  height: calc(100% - 16px);
  background: #fff7e6;
  transform: scaleY(0);
  transform-origin: top;
}
@supports (animation-timeline: scroll()) {
  .timeline__line {
    animation: line-draw linear both;
    animation-timeline: scroll(root);
    animation-range: 0 200px;
  }
}
@supports not (animation-timeline: scroll()) {
  .timeline__line {
    transform: scaleY(1);
  }
}

@keyframes dot-light {
  from {
    opacity: 0.28;
    transform: scale(1);
  }
  to {
    opacity: 1;
    transform: scale(1.3);
  }
}
@keyframes line-draw {
  from {
    transform: scaleY(0);
  }
  to {
    transform: scaleY(1);
  }
}
.timeline.is-demo .timeline__line {
  animation: line-draw-loop 2s ease-in-out infinite;
}

.timeline.is-demo .timeline__step:nth-child(1) .timeline__dot {
  animation: dot-loop 2s ease-out infinite;
  animation-delay: 0ms;
}

.timeline.is-demo .timeline__step:nth-child(2) .timeline__dot {
  animation: dot-loop 2s ease-out infinite;
  animation-delay: 160ms;
}

.timeline.is-demo .timeline__step:nth-child(3) .timeline__dot {
  animation: dot-loop 2s ease-out infinite;
  animation-delay: 320ms;
}

@keyframes line-draw-loop {
  0% {
    transform: scaleY(0);
  }
  60% {
    transform: scaleY(1);
  }
  100% {
    transform: scaleY(1);
  }
}
@keyframes dot-loop {
  0% {
    opacity: 0.28;
    transform: scale(1);
  }
  15% {
    opacity: 1;
    transform: scale(1.3);
  }
  70% {
    opacity: 1;
    transform: scale(1);
  }
  85% {
    opacity: 0.28;
    transform: scale(1);
  }
  100% {
    opacity: 0.28;
    transform: scale(1);
  }
}
@media (prefers-reduced-motion: reduce) {
  .timeline__line, .timeline.is-demo .timeline__line {
    animation: none !important;
    transform: scaleY(1);
  }
  .timeline__dot, .timeline.is-demo .timeline__step .timeline__dot {
    animation: none !important;
    opacity: 1;
    transform: scale(1);
  }
}

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

export type LineDrawTimelineProps = {
  steps: string[];
  /** 선 두께 (기본 2px) */
  thickness?: number;
  /** 선·점 색 (기본 cream) */
  color?: string;
  className?: string;
};

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

export default function LineDrawTimeline({
  steps,
  thickness = 2,
  color = "#fff7e6",
  className = "",
}: LineDrawTimelineProps) {
  const vars: Vars = { "--thickness": `${thickness}px`, "--color": color };

  return (
    <ul className={`${styles.timeline} ${className}`} style={vars}>
      {steps.map((step) => (
        <li key={step} className={styles.step}>
          <span className={styles.dot} />
          {step}
        </li>
      ))}
      <li className={styles.line} aria-hidden="true" />
    </ul>
  );
}