/**
 * Living Canvas · Skeleton System v1.0
 * 流式加载占位 + 渐隐过渡
 *
 * 引入方式：<link rel="stylesheet" href="../libs/skeleton-system.css">
 *
 * 用法：
 *   <div class="skeleton skeleton-text"></div>        — 单行文本
 *   <div class="skeleton skeleton-text-block"></div>  — 多行段落
 *   <div class="skeleton skeleton-card"></div>        — 卡片占位
 *   <div class="skeleton skeleton-avatar"></div>      — 头像圆形
 *   <div class="skeleton skeleton-button"></div>      — 按钮
 *   <div class="skeleton skeleton-image"></div>       — 图片区域
 *
 * 加载完成后：
 *   element.classList.add('skeleton-loaded') → 渐隐消失
 *   或 JS: LCMotion.skeletonReveal(container) → 子元素依次显现
 */

/* ── 基础骨架 ── */
.skeleton {
  position: relative;
  overflow: hidden;
  background: rgba(255, 255, 255, 0.04);
  border-radius: 12px;
  pointer-events: none;
}

.skeleton::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    90deg,
    transparent 0%,
    rgba(255, 255, 255, 0.06) 20%,
    rgba(255, 255, 255, 0.12) 50%,
    rgba(255, 255, 255, 0.06) 80%,
    transparent 100%
  );
  transform: translateX(-100%);
  animation: skeleton-sweep 2s cubic-bezier(0.16, 1, 0.3, 1) infinite;
}

@keyframes skeleton-sweep {
  to { transform: translateX(100%); }
}

/* ── 形态变体 ── */
.skeleton-text {
  height: 14px;
  width: 80%;
  border-radius: 6px;
  margin-bottom: 10px;
}

.skeleton-text:last-child {
  width: 55%;
}

.skeleton-text-block {
  height: 80px;
  border-radius: 10px;
}

.skeleton-card {
  height: 200px;
  border-radius: 28px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(255, 255, 255, 0.04);
}

.skeleton-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  flex-shrink: 0;
}

.skeleton-avatar.lg {
  width: 64px;
  height: 64px;
}

.skeleton-button {
  height: 40px;
  width: 120px;
  border-radius: 100px;
}

.skeleton-image {
  height: 160px;
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.02);
}

/* ── 组合布局 ── */
.skeleton-row {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.skeleton-stack {
  display: flex;
  flex-direction: column;
  gap: 8px;
  flex: 1;
}

/* ── 加载完成过渡 ── */
.skeleton-loaded {
  animation: skeleton-fade-out 0.5s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

@keyframes skeleton-fade-out {
  to {
    opacity: 0;
    transform: scale(0.98);
    filter: blur(4px);
    pointer-events: none;
  }
}

/* 内容显现（配合 skeleton 消失） */
.skeleton-content {
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.4s cubic-bezier(0.16, 1, 0.3, 1),
              transform 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

.skeleton-content.revealed {
  opacity: 1;
  transform: translateY(0);
}

/* ── 减弱动效 ── */
@media (prefers-reduced-motion: reduce) {
  .skeleton::after {
    animation: none;
  }
  .skeleton-loaded {
    animation-duration: 0.01s;
  }
}