05Skeleton to content crossfade

<main class="stage">
  <div class="card is-demo">
    <div class="card__layer card__layer--skeleton" aria-hidden="true">
      <span class="sk sk--avatar"></span>
      <span class="card__col">
        <span class="sk sk--title"></span>
        <span class="sk sk--line"></span>
        <span class="sk sk--line sk--line--short"></span>
      </span>
    </div>
    <div class="card__layer card__layer--content">
      <span class="avatar"></span>
      <span class="card__col">
        <p class="title">Title text</p>
        <p class="body">Body content shows up here</p>
      </span>
    </div>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-enter;                              // 스켈레톤 → 콘텐츠 전환 시간
$easing: $ease-out;                                 // 시작 빠르고 끝은 부드럽게
$color: $subject-blue;                              // 콘텐츠 아바타 색

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

.card {
  position: relative;
  width: min(230px, 82vw);
  height: clamp(110px, 40vw, 130px);
  border-radius: $r-card;
  background: $subject-cream;
  box-shadow: $shadow-raised;
  overflow: hidden;
}

.card__layer {
  position: absolute; inset: 0;
  box-sizing: border-box;
  padding: clamp(14px, 5vw, 18px);
  display: flex;
  align-items: flex-start;
  gap: 12px;
}
.card__col {
  display: flex;
  flex-direction: column;
  min-width: 0;
  flex: 1;
}

// ── 스켈레톤 레이어 ──────────────────────────────────
.card__layer--skeleton {
  flex-direction: row;
  opacity: 1;
  transform: scale(1);
  transition: opacity $duration $easing, transform $duration $easing;
}
.sk {
  display: block;
  border-radius: $r-control;
  background: rgba($stage-ink, .12);
}
.sk--avatar { width: 34px; height: 34px; border-radius: 50%; flex: none; }
.sk--title  { width: 110px; height: 14px; margin-bottom: 10px; }
.sk--line   { display: block; width: 130px; height: 10px; margin-top: 8px; }
.sk--line--short { width: 85px; }

// ── 콘텐츠 레이어 ────────────────────────────────────
.card__layer--content {
  flex-direction: row;
  align-items: flex-start;
  opacity: 0;
  transform: scale(.98);
  transition: opacity $duration $easing, transform $duration $easing;
}
.avatar {
  width: 34px; height: 34px; border-radius: 50%; flex: none;
  background: $color;
}
.title { margin: 0 0 6px; color: $stage-ink; font-weight: 700; font-size: clamp(13px, 3.8vw, 15px); line-height: 1.3; font-family: inherit; }
.body  { margin: 0; color: rgba($stage-ink, .68); font-weight: 500; font-size: clamp(12px, 3.4vw, 13px); line-height: 1.4; font-family: inherit; }

.card.is-demo {
  .card__layer--skeleton { animation: sk-fade $dur-loop $easing infinite; }
  .card__layer--content  { animation: content-fade $dur-loop $easing infinite; }
}

@keyframes sk-fade {
  0%, 12%  { opacity: 1; transform: scale(1); }
  55%, 100% { opacity: 0; transform: scale(1.02); }
}
@keyframes content-fade {
  0%, 12%  { opacity: 0; transform: scale(.98); }
  55%, 100% { opacity: 1; transform: scale(1); }
}

// ── 접근성: 움직임 줄이기 설정이면 콘텐츠 상태로 고정 ────────
@media (prefers-reduced-motion: reduce) {
  .card__layer--skeleton, .card__layer--content { transition: none; }
  .card.is-demo .card__layer--skeleton,
  .card.is-demo .card__layer--content { animation: none !important; }
  .card .card__layer--skeleton { opacity: 0; }
  .card .card__layer--content  { 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);
}

.card {
  position: relative;
  width: min(230px, 82vw);
  height: clamp(110px, 40vw, 130px);
  border-radius: 16px;
  background: #fff7e6;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  overflow: hidden;
}

.card__layer {
  position: absolute;
  inset: 0;
  box-sizing: border-box;
  padding: clamp(14px, 5vw, 18px);
  display: flex;
  align-items: flex-start;
  gap: 12px;
}

.card__col {
  display: flex;
  flex-direction: column;
  min-width: 0;
  flex: 1;
}

.card__layer--skeleton {
  flex-direction: row;
  opacity: 1;
  transform: scale(1);
  transition: opacity 600ms ease-out, transform 600ms ease-out;
}

.sk {
  display: block;
  border-radius: 12px;
  background: rgba(23, 20, 26, 0.12);
}

.sk--avatar {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  flex: none;
}

.sk--title {
  width: 110px;
  height: 14px;
  margin-bottom: 10px;
}

.sk--line {
  display: block;
  width: 130px;
  height: 10px;
  margin-top: 8px;
}

.sk--line--short {
  width: 85px;
}

.card__layer--content {
  flex-direction: row;
  align-items: flex-start;
  opacity: 0;
  transform: scale(0.98);
  transition: opacity 600ms ease-out, transform 600ms ease-out;
}

.avatar {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  flex: none;
  background: #2f6df6;
}

.title {
  margin: 0 0 6px;
  color: #17141a;
  font-weight: 700;
  font-size: clamp(13px, 3.8vw, 15px);
  line-height: 1.3;
  font-family: inherit;
}

.body {
  margin: 0;
  color: rgba(23, 20, 26, 0.68);
  font-weight: 500;
  font-size: clamp(12px, 3.4vw, 13px);
  line-height: 1.4;
  font-family: inherit;
}

.card.is-demo .card__layer--skeleton {
  animation: sk-fade 2s ease-out infinite;
}
.card.is-demo .card__layer--content {
  animation: content-fade 2s ease-out infinite;
}

@keyframes sk-fade {
  0%, 12% {
    opacity: 1;
    transform: scale(1);
  }
  55%, 100% {
    opacity: 0;
    transform: scale(1.02);
  }
}
@keyframes content-fade {
  0%, 12% {
    opacity: 0;
    transform: scale(0.98);
  }
  55%, 100% {
    opacity: 1;
    transform: scale(1);
  }
}
@media (prefers-reduced-motion: reduce) {
  .card__layer--skeleton, .card__layer--content {
    transition: none;
  }
  .card.is-demo .card__layer--skeleton,
  .card.is-demo .card__layer--content {
    animation: none !important;
  }
  .card .card__layer--skeleton {
    opacity: 0;
  }
  .card .card__layer--content {
    opacity: 1;
    transform: scale(1);
  }
}

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

export type SkeletonToContentCardProps = {
  loading: boolean;
  title: string;
  body: string;
  /** 전환 시간 (기본 600ms) */
  duration?: number;
  easing?: string;
  color?: string;
};

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

export default function SkeletonToContentCard({
  loading,
  title,
  body,
  duration = 600,
  easing = "ease-out",
  color = "#2f6df6",
}: SkeletonToContentCardProps) {
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  return (
    <div className={styles.card} style={vars}>
      <div className={styles.layer} style={{ opacity: loading ? 1 : 0 }} aria-hidden="true">
        <span className={`${styles.sk} ${styles.avatar}`} />
        <div>
          <span className={`${styles.sk} ${styles.title}`} />
          <span className={`${styles.sk} ${styles.line}`} />
          <span className={`${styles.sk} ${styles.lineShort}`} />
        </div>
      </div>
      <div className={styles.layer} style={{ opacity: loading ? 0 : 1, transform: loading ? "scale(.98)" : "scale(1)" }}>
        <span className={styles.realAvatar} />
        <div>
          <p className={styles.realTitle}>{title}</p>
          <p className={styles.realBody}>{body}</p>
        </div>
      </div>
    </div>
  );
}