/* 尿素设备 - 电子书风格样式表 */
/* 主色调: #795548 (棕色) */

/* CSS 变量 */
:root {
  --accent-color: #795548;
  --accent-light: #8d6e63;
  --accent-dark: #5d4037;
  --text-primary: #333;
  --text-secondary: #666;
  --text-muted: #999;
  --bg-primary: #fff;
  --bg-secondary: #fafafa;
  --bg-warm: #f5f0eb;
  --border-color: #e0e0e0;
  --shadow: 0 2px 8px rgba(0,0,0,0.1);
  --shadow-hover: 0 4px 16px rgba(0,0,0,0.15);
  --radius: 4px;
  --max-width: 1200px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-serif: Georgia, "Times New Roman", serif;
}

/* 重置 */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-secondary);
}

a {
  color: var(--accent-color);
  text-decoration: none;
}

a:hover {
  color: var(--accent-dark);
}

img {
  max-width: 100%;
  height: auto;
}

/* 容器 */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* 页头 */
.header {
  background: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  padding: 16px 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

.header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.logo {
  font-size: 24px;
  font-weight: 700;
  color: var(--accent-color);
  display: flex;
  align-items: center;
  gap: 8px;
}

.logo::before {
  content: "📚";
}

.nav {
  display: flex;
  gap: 32px;
}

.nav a {
  color: var(--text-secondary);
  font-size: 15px;
  font-weight: 500;
}

.nav a:hover,
.nav a.active {
  color: var(--accent-color);
}

.search-box {
  display: flex;
  align-items: center;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 20px;
  padding: 8px 16px;
  min-width: 240px;
}

.search-box input {
  border: none;
  background: none;
  outline: none;
  font-size: 14px;
  width: 100%;
}

.search-box::before {
  content: "🔍";
  margin-right: 8px;
  opacity: 0.5;
}

/* Hero 区域 */
.hero {
  background: linear-gradient(135deg, var(--bg-warm) 0%, var(--bg-secondary) 100%);
  padding: 60px 0;
  text-align: center;
}

.hero h1 {
  font-size: 36px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.hero p {
  font-size: 18px;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* 区块标题 */
.section-title {
  font-size: 22px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 24px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--accent-color);
  display: inline-block;
}

/* 内容区块 */
.section {
  padding: 40px 0;
}

.section-alt {
  background: var(--bg-primary);
}

/* 书籍网格 */
.book-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 24px;
}

.book-card {
  background: var(--bg-primary);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: transform 0.2s, box-shadow 0.2s;
}

.book-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.book-cover {
  aspect-ratio: 3/4;
  background: linear-gradient(135deg, var(--accent-light) 0%, var(--accent-color) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 48px;
}

.book-info {
  padding: 16px;
}

.book-title {
  font-size: 15px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 6px;
  line-height: 1.4;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.book-meta {
  font-size: 13px;
  color: var(--text-muted);
}

/* 分类网格 */
.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
}

.category-card {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 24px;
  text-align: center;
  transition: all 0.2s;
}

.category-card:hover {
  border-color: var(--accent-color);
  box-shadow: var(--shadow);
}

.category-icon {
  font-size: 32px;
  margin-bottom: 12px;
}

.category-name {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.category-count {
  font-size: 13px;
  color: var(--text-muted);
}

/* 书籍列表 */
.book-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.book-list-item {
  display: flex;
  gap: 16px;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 16px;
  transition: all 0.2s;
}

.book-list-item:hover {
  border-color: var(--accent-color);
}

.book-list-cover {
  width: 80px;
  height: 100px;
  background: linear-gradient(135deg, var(--accent-light) 0%, var(--accent-color) 100%);
  border-radius: var(--radius);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 24px;
}

.book-list-info {
  flex: 1;
}

.book-list-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.book-list-desc {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* 三栏文章列表 */
.article-columns {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

.article-column h3 {
  font-size: 16px;
  font-weight: 600;
  color: var(--accent-color);
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-color);
}

.article-list {
  list-style: none;
}

.article-list li {
  padding: 10px 0;
  border-bottom: 1px dashed var(--border-color);
}

.article-list li:last-child {
  border-bottom: none;
}

.article-list a {
  color: var(--text-secondary);
  font-size: 14px;
  display: block;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.article-list a:hover {
  color: var(--accent-color);
}

.article-list a::before {
  content: "•";
  color: var(--accent-color);
  margin-right: 8px;
}

/* 面包屑 */
.breadcrumb {
  padding: 16px 0;
  background: var(--bg-warm);
  border-bottom: 1px solid var(--border-color);
}

.breadcrumb ol {
  list-style: none;
  display: flex;
  gap: 8px;
  font-size: 14px;
}

.breadcrumb li:not(:last-child)::after {
  content: ">";
  margin-left: 8px;
  color: var(--text-muted);
}

.breadcrumb a {
  color: var(--text-secondary);
}

.breadcrumb a:hover {
  color: var(--accent-color);
}

.breadcrumb li:last-child {
  color: var(--text-primary);
  font-weight: 500;
}

/* 页面头部 */
.page-header {
  padding: 40px 0;
  background: var(--bg-warm);
  text-align: center;
}

.page-header h1 {
  font-size: 28px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.page-header p {
  font-size: 15px;
  color: var(--text-secondary);
}

/* 筛选排序 */
.filter-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 0;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 24px;
}

.filter-options {
  display: flex;
  gap: 16px;
}

.filter-options a {
  font-size: 14px;
  color: var(--text-secondary);
  padding: 6px 12px;
  border-radius: var(--radius);
}

.filter-options a.active,
.filter-options a:hover {
  background: var(--accent-color);
  color: #fff;
}

.result-count {
  font-size: 14px;
  color: var(--text-muted);
}

/* 分页 */
.pagination {
  display: flex;
  justify-content: center;
  gap: 8px;
  padding: 32px 0;
}

.pagination a,
.pagination span {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius);
  font-size: 14px;
}

.pagination a {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
}

.pagination a:hover {
  border-color: var(--accent-color);
  color: var(--accent-color);
}

.pagination .current {
  background: var(--accent-color);
  color: #fff;
}

/* 文章页布局 */
.article-layout {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 40px;
  padding: 32px 0;
}

/* 主内容 */
.main-content {
  background: var(--bg-primary);
  border-radius: var(--radius);
  padding: 40px;
  box-shadow: var(--shadow);
}

.article-header {
  margin-bottom: 32px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border-color);
}

.article-title {
  font-size: 28px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 16px;
  line-height: 1.4;
}

.article-meta {
  display: flex;
  gap: 24px;
  font-size: 14px;
  color: var(--text-muted);
}

.article-meta span {
  display: flex;
  align-items: center;
  gap: 6px;
}

.article-body {
  font-size: 16px;
  line-height: 1.8;
  color: var(--text-primary);
}

.article-body h2 {
  font-size: 22px;
  font-weight: 600;
  margin: 32px 0 16px;
  color: var(--text-primary);
}

.article-body h3 {
  font-size: 18px;
  font-weight: 600;
  margin: 24px 0 12px;
  color: var(--text-primary);
}

.article-body p {
  margin-bottom: 16px;
}

.article-body ul,
.article-body ol {
  margin-bottom: 16px;
  padding-left: 24px;
}

.article-body li {
  margin-bottom: 8px;
}

/* 侧边栏 */
.sidebar {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.sidebar-widget {
  background: var(--bg-primary);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

.widget-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--accent-color);
}

.toc-list {
  list-style: none;
}

.toc-list li {
  padding: 8px 0;
  border-bottom: 1px solid var(--border-color);
}

.toc-list li:last-child {
  border-bottom: none;
}

.toc-list a {
  font-size: 14px;
  color: var(--text-secondary);
  display: block;
}

.toc-list a:hover {
  color: var(--accent-color);
}

.toc-list .toc-h2 {
  font-weight: 500;
  color: var(--text-primary);
}

.toc-list .toc-h3 {
  padding-left: 16px;
  font-size: 13px;
}

/* 书籍详情 */
.book-detail {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 32px;
  margin-bottom: 32px;
}

.book-detail-cover {
  aspect-ratio: 3/4;
  background: linear-gradient(135deg, var(--accent-light) 0%, var(--accent-color) 100%);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 64px;
  box-shadow: var(--shadow);
}

.book-detail-info h1 {
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 12px;
}

.book-detail-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 16px;
}

.book-detail-desc {
  font-size: 15px;
  line-height: 1.7;
  color: var(--text-secondary);
}

.book-info-list {
  list-style: none;
  margin-top: 24px;
}

.book-info-list li {
  padding: 8px 0;
  font-size: 14px;
  color: var(--text-secondary);
  border-bottom: 1px dashed var(--border-color);
}

.book-info-list li:last-child {
  border-bottom: none;
}

.book-info-list strong {
  color: var(--text-primary);
  display: inline-block;
  width: 100px;
}

/* 推荐文章横向 */
.related-articles {
  background: var(--bg-warm);
  padding: 24px;
  border-radius: var(--radius);
  margin-bottom: 32px;
}

.related-title {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.related-list {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
}

.related-list a {
  font-size: 14px;
  color: var(--text-secondary);
  padding: 8px 16px;
  background: var(--bg-primary);
  border-radius: 20px;
  border: 1px solid var(--border-color);
}

.related-list a:hover {
  border-color: var(--accent-color);
  color: var(--accent-color);
}

/* 404 页面 */
.error-page {
  min-height: 60vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 60px 20px;
}

.error-code {
  font-size: 120px;
  font-weight: 700;
  color: var(--accent-color);
  line-height: 1;
  margin-bottom: 16px;
  opacity: 0.8;
}

.error-title {
  font-size: 28px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.error-desc {
  font-size: 16px;
  color: var(--text-secondary);
  margin-bottom: 32px;
  max-width: 400px;
}

.error-actions {
  display: flex;
  gap: 16px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: var(--radius);
  font-size: 15px;
  font-weight: 500;
  transition: all 0.2s;
}

.btn-primary {
  background: var(--accent-color);
  color: #fff;
}

.btn-primary:hover {
  background: var(--accent-dark);
  color: #fff;
}

.btn-secondary {
  background: var(--bg-primary);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
}

.btn-secondary:hover {
  border-color: var(--accent-color);
  color: var(--accent-color);
}

/* 页脚 */
.footer {
  background: var(--bg-primary);
  border-top: 1px solid var(--border-color);
  padding: 40px 0 24px;
  margin-top: 40px;
}

.footer-content {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 32px;
}

.footer-brand {
  font-size: 20px;
  font-weight: 700;
  color: var(--accent-color);
  margin-bottom: 12px;
}

.footer-desc {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.6;
}

.footer-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: 10px;
}

.footer-links a {
  font-size: 14px;
  color: var(--text-secondary);
}

.footer-links a:hover {
  color: var(--accent-color);
}

.footer-bottom {
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
  text-align: center;
  font-size: 13px;
  color: var(--text-muted);
}

/* 响应式设计 */
@media (max-width: 992px) {
  .article-layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    order: -1;
  }

  .book-detail {
    grid-template-columns: 180px 1fr;
  }

  .footer-content {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  .header .container {
    flex-wrap: wrap;
  }

  .nav {
    order: 3;
    width: 100%;
    justify-content: center;
    gap: 20px;
  }

  .search-box {
    min-width: auto;
    flex: 1;
  }

  .hero {
    padding: 40px 0;
  }

  .hero h1 {
    font-size: 28px;
  }

  .article-columns {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .book-detail {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .book-detail-cover {
    max-width: 200px;
    margin: 0 auto;
  }

  .main-content {
    padding: 24px;
  }

  .article-title {
    font-size: 22px;
  }

  .footer-content {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .error-code {
    font-size: 80px;
  }
}

@media (max-width: 480px) {
  .book-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
  }

  .category-grid {
    grid-template-columns: 1fr;
  }

  .filter-bar {
    flex-direction: column;
    gap: 12px;
    align-items: flex-start;
  }

  .article-meta {
    flex-wrap: wrap;
    gap: 12px;
  }
}