/* ============================================
   人体工学椅 - 学术风格样式表
   主色调: #607d8b (蓝灰色)
   ============================================ */

/* CSS 变量定义 */
:root {
  --primary-color: #607d8b;
  --primary-dark: #455a64;
  --primary-light: #90a4ae;
  --text-primary: #333;
  --text-secondary: #666;
  --text-muted: #888;
  --bg-primary: #fff;
  --bg-secondary: #f5f7f8;
  --bg-tertiary: #eceff1;
  --border-color: #e0e0e0;
  --link-color: #607d8b;
  --link-hover: #455a64;
  --accent-color: #607d8b;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 2px 8px rgba(0,0,0,0.1);
  --radius-sm: 4px;
  --radius-md: 8px;
  --max-width: 1200px;
  --content-width: 800px;
}

/* 重置样式 */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", sans-serif;
  font-size: 1rem;
  line-height: 1.7;
  color: var(--text-primary);
  background-color: var(--bg-primary);
}

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

a {
  color: var(--link-color);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--link-hover);
}

ul, ol {
  list-style: none;
}

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

.content-wrapper {
  max-width: var(--content-width);
  margin: 0 auto;
}

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

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
}

.logo a {
  color: inherit;
}

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

.nav a {
  font-size: 0.95rem;
  color: var(--text-secondary);
  font-weight: 500;
}

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

.search-box {
  display: flex;
  align-items: center;
  gap: 8px;
}

.search-box input {
  width: 200px;
  padding: 8px 12px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  outline: none;
}

.search-box input:focus {
  border-color: var(--primary-color);
}

.search-box button {
  padding: 8px 16px;
  background-color: var(--primary-color);
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  cursor: pointer;
}

.search-box button:hover {
  background-color: var(--primary-dark);
}

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

.hero-title {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.hero-subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* ============================================
   面包屑导航
   ============================================ */
.breadcrumb {
  background-color: var(--bg-secondary);
  padding: 12px 0;
  font-size: 0.9rem;
  color: var(--text-muted);
}

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

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

.breadcrumb-separator {
  margin: 0 8px;
  color: var(--text-muted);
}

.breadcrumb-current {
  color: var(--text-primary);
}

/* ============================================
   分类卡片
   ============================================ */
.category-section {
  padding: 40px 0;
}

.section-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 24px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--primary-color);
  display: inline-block;
}

.category-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

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

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

.category-card-icon {
  width: 48px;
  height: 48px;
  background-color: var(--bg-secondary);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 16px;
  font-size: 1.5rem;
}

.category-card-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.category-card-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* ============================================
   文章列表
   ============================================ */
.article-section {
  padding: 40px 0;
}

.article-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.article-list {
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.article-list-header {
  background-color: var(--bg-secondary);
  padding: 16px 20px;
  border-bottom: 1px solid var(--border-color);
}

.article-list-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-primary);
}

.article-list-body {
  padding: 16px 20px;
}

.article-list-item {
  padding: 12px 0;
  border-bottom: 1px solid var(--border-color);
}

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

.article-list-item a {
  display: block;
  font-size: 0.95rem;
  color: var(--text-primary);
  line-height: 1.5;
}

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

.article-list-item .meta {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 4px;
}

/* ============================================
   内容卡片 (分类页/详情页)
   ============================================ */
.content-card {
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  margin-bottom: 20px;
}

.content-card-title {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.content-card-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin-bottom: 16px;
  line-height: 1.6;
}

.content-card-actions {
  display: flex;
  gap: 12px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 20px;
  font-size: 0.9rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.2s ease;
  border: none;
}

.btn-primary {
  background-color: var(--primary-color);
  color: white;
}

.btn-primary:hover {
  background-color: var(--primary-dark);
  color: white;
}

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

.btn-secondary:hover {
  background-color: var(--bg-tertiary);
}

/* ============================================
   分页
   ============================================ */
.pagination {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 8px;
  margin-top: 40px;
  padding: 20px 0;
}

.pagination a,
.pagination span {
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 40px;
  height: 40px;
  padding: 0 12px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  color: var(--text-secondary);
  background-color: var(--bg-primary);
}

.pagination a:hover {
  background-color: var(--bg-secondary);
  color: var(--primary-color);
  border-color: var(--primary-light);
}

.pagination .current {
  background-color: var(--primary-color);
  color: white;
  border-color: var(--primary-color);
}

.pagination .prev,
.pagination .next {
  padding: 0 16px;
}

/* ============================================
   文章详情页
   ============================================ */
.article-header {
  padding: 40px 0 30px;
  text-align: center;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 40px;
}

.article-title {
  font-size: 2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 16px;
  line-height: 1.3;
}

.article-meta {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 20px;
  font-size: 0.9rem;
  color: var(--text-muted);
  flex-wrap: wrap;
}

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

.article-tags {
  display: flex;
  justify-content: center;
  gap: 8px;
  margin-top: 16px;
  flex-wrap: wrap;
}

.tag {
  display: inline-block;
  padding: 4px 12px;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.tag:hover {
  background-color: var(--bg-tertiary);
  color: var(--primary-color);
}

/* 文章正文 */
.article-body {
  font-size: 1.05rem;
  line-height: 1.8;
  color: var(--text-primary);
}

.article-body h2 {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 40px 0 20px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border-color);
}

.article-body h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
  margin: 32px 0 16px;
}

.article-body p {
  margin-bottom: 20px;
}

.article-body ul,
.article-body ol {
  margin-bottom: 20px;
  padding-left: 24px;
}

.article-body ul {
  list-style: disc;
}

.article-body ol {
  list-style: decimal;
}

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

.article-body strong {
  font-weight: 600;
  color: var(--text-primary);
}

.article-body blockquote {
  background-color: var(--bg-secondary);
  border-left: 4px solid var(--primary-color);
  padding: 16px 20px;
  margin: 24px 0;
  font-style: italic;
  color: var(--text-secondary);
}

.article-body img {
  border-radius: var(--radius-md);
  margin: 24px 0;
  box-shadow: var(--shadow-sm);
}

/* 摘要框 */
.abstract-box {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  margin-bottom: 32px;
}

.abstract-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--primary-color);
  margin-bottom: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.abstract-content {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* 关键词 */
.keywords {
  margin-top: 16px;
}

.keywords-label {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-right: 8px;
}

/* 结构列表 */
.structure-list {
  background-color: var(--bg-secondary);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  margin: 24px 0;
}

.structure-list ul {
  list-style: none;
  padding-left: 0;
}

.structure-list li {
  padding: 8px 0;
  padding-left: 24px;
  position: relative;
  border-bottom: 1px solid var(--border-color);
}

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

.structure-list li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: var(--primary-color);
  font-weight: bold;
}

/* 预览框 */
.preview-box {
  background-color: var(--bg-primary);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 32px;
  margin: 24px 0;
  font-family: Georgia, "Times New Roman", serif;
}

.preview-box-title {
  font-size: 1.5rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 8px;
}

.preview-box-author {
  text-align: center;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

.preview-box-section {
  font-weight: 700;
  margin-top: 20px;
  margin-bottom: 8px;
}

.preview-box-content {
  color: var(--text-secondary);
  line-height: 1.6;
}

/* 下载选项 */
.download-section {
  margin: 32px 0;
  padding: 24px;
  background-color: var(--bg-secondary);
  border-radius: var(--radius-md);
  text-align: center;
}

.download-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 16px;
}

.download-options {
  display: flex;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}

/* ============================================
   侧边栏组件
   ============================================ */
.sidebar-section {
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: 24px;
  overflow: hidden;
}

.sidebar-header {
  background-color: var(--bg-secondary);
  padding: 16px 20px;
  border-bottom: 1px solid var(--border-color);
}

.sidebar-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
}

.sidebar-body {
  padding: 16px 20px;
}

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

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

.sidebar-list a {
  font-size: 0.95rem;
  color: var(--text-primary);
  display: block;
}

.sidebar-list a:hover {
  color: var(--primary-color);
}

/* ============================================
   两栏布局
   ============================================ */
.two-column {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 40px;
}

.main-content {
  min-width: 0;
}

.sidebar {
  min-width: 0;
}

/* ============================================
   页脚 Footer
   ============================================ */
.footer {
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 40px 0 20px;
  margin-top: 60px;
}

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

.footer-brand {
  max-width: 300px;
}

.footer-logo {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--primary-color);
  margin-bottom: 12px;
}

.footer-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.footer-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 16px;
}

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

.footer-links a {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

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

.footer-bottom {
  border-top: 1px solid var(--border-color);
  padding-top: 20px;
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* ============================================
   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: 8rem;
  font-weight: 700;
  color: var(--primary-light);
  line-height: 1;
  margin-bottom: 16px;
}

.error-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.error-desc {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 32px;
  max-width: 400px;
}

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

/* ============================================
   响应式设计
   ============================================ */
@media (max-width: 1024px) {
  .two-column {
    grid-template-columns: 1fr;
  }

  .sidebar {
    order: 2;
  }

  .footer-inner {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .header-inner {
    flex-wrap: wrap;
    height: auto;
    padding: 12px 0;
    gap: 12px;
  }

  .nav {
    order: 3;
    width: 100%;
    justify-content: center;
    gap: 20px;
    padding-top: 8px;
    border-top: 1px solid var(--border-color);
  }

  .search-box {
    order: 2;
  }

  .search-box input {
    width: 150px;
  }

  .hero {
    padding: 40px 0;
  }

  .hero-title {
    font-size: 1.8rem;
  }

  .hero-subtitle {
    font-size: 1rem;
  }

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

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

  .article-title {
    font-size: 1.5rem;
  }

  .article-meta {
    flex-direction: column;
    gap: 8px;
  }

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

  .error-code {
    font-size: 5rem;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 16px;
  }

  .nav {
    font-size: 0.85rem;
    gap: 12px;
  }

  .search-box input {
    width: 120px;
    padding: 6px 10px;
  }

  .search-box button {
    padding: 6px 12px;
  }

  .content-card {
    padding: 16px;
  }

  .content-card-actions {
    flex-direction: column;
  }

  .btn {
    width: 100%;
  }

  .pagination a,
  .pagination span {
    min-width: 36px;
    height: 36px;
    font-size: 0.9rem;
  }

  .download-options {
    flex-direction: column;
  }
}

/* ============================================
   辅助类
   ============================================ */
.text-center {
  text-align: center;
}

.mt-20 {
  margin-top: 20px;
}

.mt-40 {
  margin-top: 40px;
}

.mb-20 {
  margin-bottom: 20px;
}

.mb-40 {
  margin-bottom: 40px;
}

.hidden {
  display: none;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}