01スクロールでプランがリビール

<main class="stage">
  <div class="sr-grid is-demo">
    <div class="sr-card">
      <span class="sr-card__tag">Basic</span>
      <span class="sr-card__price">$9</span>
    </div>
    <div class="sr-card sr-card--mid">
      <span class="sr-card__tag">Pro</span>
      <span class="sr-card__price">$29</span>
    </div>
    <div class="sr-card">
      <span class="sr-card__tag">Team</span>
      <span class="sr-card__price">$79</span>
    </div>
  </div>
</main>

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

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

@include stage($stage-ink);

.sr-grid {
  width: min(340px, 90vw);
  aspect-ratio: 340 / 190;
  display: flex;
  align-items: flex-end;
  gap: $sp-2;
}

.sr-card {
  flex: 1 1 0;
  height: 78%;
  border-radius: $r-sm;
  box-sizing: border-box;
  padding: $sp-3;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  gap: $sp-1;
  color: $subject-cream;
  background: rgba(255, 255, 255, .08);
  font: 600 12px/1 -apple-system, "Segoe UI", sans-serif;
}

.sr-card--mid {
  height: 100%;
  background: $subject-blue-deep;   // 크림 글자가 얹히므로 진한 파랑
}

.sr-card__tag { opacity: 1; font-size: 11px; }      // AA: 진한 파랑 면 위 크림 100% — 5.98:1
.sr-card__price { font-size: 20px; font-weight: 700; margin-top: $sp-1; }

// 실사용: IntersectionObserver 가 .sr-grid 에 .in 을 붙이면 카드가 순서대로 떠오른다
.sr-card {
  opacity: 0;
  transform: translateY($sp-4);
  transition: opacity 400ms $easing, transform 400ms $easing;
}
.sr-grid.in .sr-card { opacity: 1; transform: none; }
.sr-grid.in .sr-card:nth-child(2) { transition-delay: 140ms; }
.sr-grid.in .sr-card:nth-child(3) { transition-delay: 280ms; }

// 데모 루프: is-demo 는 실사용 경로(.in, 실제 스크롤 진입)와 별개로 keyframes 로 반복 재생 (캡처용)
@keyframes sr-rise {
  0% { opacity: 0; transform: translateY($sp-4); }
  20%, 85% { opacity: 1; transform: none; }
  100% { opacity: 0; transform: translateY($sp-4); }
}
.sr-grid.is-demo .sr-card { animation: sr-rise $duration $easing infinite; }
.sr-grid.is-demo .sr-card:nth-child(2) { animation-delay: 160ms; }
.sr-grid.is-demo .sr-card:nth-child(3) { animation-delay: 320ms; }

@media (prefers-reduced-motion: reduce) {
  .sr-card,
  .sr-grid.is-demo .sr-card {
    animation: none !important;
    transition: none !important;
    opacity: 1 !important;
    transform: none !important;
  }
}

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);
}

.sr-grid {
  width: min(340px, 90vw);
  aspect-ratio: 340/190;
  display: flex;
  align-items: flex-end;
  gap: 8px;
}

.sr-card {
  flex: 1 1 0;
  height: 78%;
  border-radius: 8px;
  box-sizing: border-box;
  padding: 12px;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  gap: 4px;
  color: #fff7e6;
  background: rgba(255, 255, 255, 0.08);
  font: 600 12px/1 -apple-system, "Segoe UI", sans-serif;
}

.sr-card--mid {
  height: 100%;
  background: #0a4fe8;
}

.sr-card__tag {
  opacity: 1;
  font-size: 11px;
}

.sr-card__price {
  font-size: 20px;
  font-weight: 700;
  margin-top: 4px;
}

.sr-card {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 400ms ease-out, transform 400ms ease-out;
}

.sr-grid.in .sr-card {
  opacity: 1;
  transform: none;
}

.sr-grid.in .sr-card:nth-child(2) {
  transition-delay: 140ms;
}

.sr-grid.in .sr-card:nth-child(3) {
  transition-delay: 280ms;
}

@keyframes sr-rise {
  0% {
    opacity: 0;
    transform: translateY(16px);
  }
  20%, 85% {
    opacity: 1;
    transform: none;
  }
  100% {
    opacity: 0;
    transform: translateY(16px);
  }
}
.sr-grid.is-demo .sr-card {
  animation: sr-rise 2s ease-out infinite;
}

.sr-grid.is-demo .sr-card:nth-child(2) {
  animation-delay: 160ms;
}

.sr-grid.is-demo .sr-card:nth-child(3) {
  animation-delay: 320ms;
}

@media (prefers-reduced-motion: reduce) {
  .sr-card,
  .sr-grid.is-demo .sr-card {
    animation: none !important;
    transition: none !important;
    opacity: 1 !important;
    transform: none !important;
  }
}

var grid = document.querySelector('.sr-grid');
  var io = new IntersectionObserver(function (entries) {
    entries.forEach(function (e) {
      if (e.isIntersecting) { grid.classList.add('in'); io.unobserve(grid); }
    });
  }, { threshold: 0.3 });
  io.observe(grid);

import { CSSProperties, useEffect, useRef, useState } from "react";
import styles from "./PlansRevealOnScroll.module.scss";

export interface PlansRevealOnScrollProps {
  duration?: string;
  easing?: string;
  stagger?: string;
}

const PLANS = [
  { tag: "Basic", price: "$9" },
  { tag: "Pro", price: "$29" },
  { tag: "Team", price: "$79" },
];

// 실사용: 진짜 IntersectionObserver 가 그리드가 뷰포트에 들어올 때 in 을 켠다. 카드마다 transition-delay 만 다르다.
export default function PlansRevealOnScroll({
  duration = "400ms",
  easing = "ease-out",
  stagger = "140ms",
}: PlansRevealOnScrollProps) {
  const gridRef = useRef<HTMLDivElement>(null);
  const [inView, setInView] = useState(false);

  useEffect(() => {
    const el = gridRef.current;
    if (!el) return;
    const io = new IntersectionObserver((entries) => {
      entries.forEach((e) => { if (e.isIntersecting) { setInView(true); io.unobserve(e.target); } });
    }, { threshold: 0.3 });
    io.observe(el);
    return () => io.disconnect();
  }, []);

  const style = { "--duration": duration, "--easing": easing } as CSSProperties;

  return (
    <div className={styles.grid} style={style} ref={gridRef}>
      {PLANS.map((p, i) => (
        <div
          key={p.tag}
          className={`${styles.card} ${i === 1 ? styles.mid : ""} ${inView ? styles.in : ""}`}
          style={{ transitionDelay: inView ? `calc(${stagger} * ${i})` : undefined }}
        >
          <span className={styles.tag}>{p.tag}</span>
          <span className={styles.price}>{p.price}</span>
        </div>
      ))}
    </div>
  );
}