/* ===== Reset & Variables ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #fffef8;
  --text: #4a3f35;
  --accent: #e8b4b8;
  --accent2: #a8d8ea;
  --card-bg: #fffdf9;
  --shadow: rgba(74, 63, 53, 0.12);
  --radius: 16px;
  --radius-sm: 10px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

/* ===== 顶部导航 ===== */
.header {
  background: linear-gradient(135deg, #fff 0%, #fef6e4 100%);
  border-bottom: 3px solid var(--accent);
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.header-logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text);
}

.header-search {
  display: flex;
  align-items: center;
  background: #fff;
  border: 2px solid #eee;
  border-radius: 24px;
  padding: 0.4rem 1rem;
  transition: border-color 0.2s;
}

.header-search:focus-within {
  border-color: var(--accent);
}

.header-search input {
  border: none;
  outline: none;
  font-size: 0.9rem;
  background: transparent;
  width: 160px;
  color: var(--text);
}

.header-search input::placeholder {
  color: #bbb;
}

/* ===== 分类标签 ===== */
.categories {
  background: var(--card-bg);
  padding: 0.8rem 1.5rem;
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  border-bottom: 1px solid #f0f0f0;
}

.category-tag {
  padding: 0.35rem 1rem;
  border-radius: 20px;
  font-size: 0.85rem;
  cursor: pointer;
  border: none;
  background: #f0f0f0;
  color: #888;
  transition: all 0.2s;
  user-select: none;
}

.category-tag:hover {
  background: #e8e8e8;
  color: var(--text);
}

.category-tag.active {
  background: var(--accent);
  color: #fff;
  font-weight: 600;
}

/* ===== 信息栏 ===== */
.shelf-info {
  padding: 1rem 1.5rem 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: #999;
}

/* ===== 书架网格 ===== */
.shelf-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.2rem;
  padding: 1rem 1.5rem 2rem;
}

/* ===== 绘本卡片 ===== */
.book-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 4px 16px var(--shadow);
  cursor: pointer;
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.book-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 28px rgba(74, 63, 53, 0.18);
}

.book-card:active {
  transform: translateY(-1px);
}

.book-cover {
  aspect-ratio: 4 / 3;
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 4rem;
  overflow: hidden;
  position: relative;
}

.book-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.book-cover .fallback {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 4rem;
}

/* 各分类封面渐变背景 */
.book-cover.category-动物 {
  background: linear-gradient(135deg, #fef6e4, #e8b4b8);
}
.book-cover.category-食物 {
  background: linear-gradient(135deg, #fff3e0, #f8bbd0);
}
.book-cover.category-生活 {
  background: linear-gradient(135deg, #e0f7fa, #b2ebf2);
}
.book-cover.category-认知 {
  background: linear-gradient(135deg, #e8f5e9, #a5d6a7);
}
.book-cover.category-其他 {
  background: linear-gradient(135deg, #f3e5f5, #e1bee7);
}

.book-info {
  padding: 0.8rem 1rem;
}

.book-title {
  font-weight: 600;
  font-size: 0.95rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.book-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 0.4rem;
}

.book-date {
  font-size: 0.75rem;
  color: #bbb;
}

.book-category-tag {
  font-size: 0.7rem;
  padding: 0.1rem 0.5rem;
  border-radius: 10px;
  background: #fef6e4;
  color: #b8860b;
}

/* ===== 空状态 ===== */
.empty-state {
  text-align: center;
  padding: 4rem 2rem;
  color: #bbb;
}

.empty-state .emoji {
  font-size: 4rem;
  margin-bottom: 1rem;
}

.empty-state p {
  font-size: 1.1rem;
}

/* ===== 底部 ===== */
.footer {
  background: linear-gradient(135deg, #e8f4f8, #fef6e4);
  padding: 1rem;
  text-align: center;
  font-size: 0.8rem;
  color: #bbb;
}

/* ===== 响应式 ===== */
@media (max-width: 1023px) {
  .shelf-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
    padding: 0.8rem 1rem 1.5rem;
  }
  .header {
    padding: 0.8rem 1rem;
  }
  .categories {
    padding: 0.6rem 1rem;
  }
}

@media (max-width: 480px) {
  .shelf-grid {
    gap: 0.8rem;
  }
  .header-logo {
    font-size: 1.1rem;
  }
  .header-search input {
    width: 120px;
  }
}