/* 皮革工艺 - 白皮书风格样式 */
:root {
  --accent-color: #8B4513;
  --accent-light: #D2691E;
  --bg-primary: #FAFAFA;
  --bg-secondary: #F5F5F5;
  --text-primary: #333;
  --text-secondary: #666;
  --text-muted: #999;
  --border-color: #E0E0E0;
  --white: #FFFFFF;
  --shadow: 0 2px 8px rgba(0,0,0,0.08);
  --shadow-hover: 0 4px 16px rgba(0,0,0,0.12);
  --radius: 8px;
  --radius-lg: 12px;
  --max-width: 1200px;
  --header-height: 64px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-primary);
}

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

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

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

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-size: 20px;
  font-weight: 700;
  color: var(--accent-color);
}

.logo span {
  color: var(--text-secondary);
  font-weight: 400;
}

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

.nav a {
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 500;
}

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

.search-box {
  position: relative;
}

.search-box input {
  width: 240px;
  padding: 8px 16px 8px 36px;
  border: 1px solid var(--border-color);
  border-radius: 20px;
  font-size: 14px;
  background: var(--bg-secondary);
  transition: all 0.2s;
}

.search-box input:focus {
  outline: none;
  border-color: var(--accent-color);
  background: var(--white);
}

.search-box::before {
  content: "🔍";
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 14px;
}

/* Hero Section */
.hero {
  background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--white) 100%);
  padding: 64px 24px;
  text-align: center;
}

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

.hero-subtitle {
  font-size: 18px;
  color: var(--text-secondary);
  margin-bottom: 32px;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.hero-search {
  max-width: 560px;
  margin: 0 auto 40px;
}

.hero-search input {
  width: 100%;
  padding: 16px 24px;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-lg);
  font-size: 16px;
  background: var(--white);
  transition: all 0.2s;
}

.hero-search input:focus {
  outline: none;
  border-color: var(--accent-color);
}

/* Categories */
.categories {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

.category-tag {
  padding: 10px 24px;
  background: var(--white);
  border: 1px solid var(--border-color);
  border-radius: 24px;
  font-size: 14px;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s;
}

.category-tag:hover,
.category-tag.active {
  background: var(--accent-color);
  border-color: var(--accent-color);
  color: var(--white);
}

/* Main Container */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 40px 24px;
}

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

/* Whitepaper Cards */
.card-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.card {
  background: var(--white);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 24px;
  transition: all 0.2s;
}

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

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 12px;
}

.card-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.card-title a {
  color: inherit;
}

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

.card-meta {
  font-size: 13px;
  color: var(--text-muted);
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.card-meta span {
  display: flex;
  align-items: center;
  gap: 4px;
}

.card-desc {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 16px;
}

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

.btn {
  padding: 8px 20px;
  border-radius: 6px;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
  border: none;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

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

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

.btn-outline {
  background: var(--white);
  color: var(--accent-color);
  border: 1px solid var(--accent-color);
}

.btn-outline:hover {
  background: var(--accent-color);
  color: var(--white);
}

/* Three Column Layout */
.three-col {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 48px;
}

.col-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  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 solid var(--border-color);
}

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

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

/* Breadcrumb */
.breadcrumb {
  background: var(--bg-secondary);
  padding: 16px 24px;
  border-bottom: 1px solid var(--border-color);
}

.breadcrumb-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  font-size: 14px;
  color: var(--text-muted);
}

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

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

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

/* Page Header */
.page-header {
  background: var(--bg-secondary);
  padding: 48px 24px;
  text-align: center;
}

.page-title {
  font-size: 28px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.page-desc {
  font-size: 16px;
  color: var(--text-secondary);
}

/* Sort Bar */
.sort-bar {
  display: flex;
  justify-content: flex-end;
  gap: 16px;
  margin-bottom: 24px;
  font-size: 14px;
  color: var(--text-secondary);
}

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

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

/* Pagination */
.pagination {
  display: flex;
  justify-content: center;
  gap: 8px;
  margin-top: 40px;
}

.pagination a,
.pagination span {
  padding: 8px 16px;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  font-size: 14px;
  color: var(--text-secondary);
  transition: all 0.2s;
}

.pagination a:hover,
.pagination a.active {
  background: var(--accent-color);
  border-color: var(--accent-color);
  color: var(--white);
}

.pagination span {
  border-color: transparent;
  cursor: default;
}

/* Article Page */
.article-header {
  text-align: center;
  margin-bottom: 40px;
}

.article-title {
  font-size: 32px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 16px;
  line-height: 1.3;
}

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

.article-cover {
  max-width: 800px;
  margin: 0 auto 40px;
}

.article-cover img {
  width: 100%;
  height: auto;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
}

/* Content Sections */
.content-section {
  background: var(--white);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 32px;
  margin-bottom: 24px;
}

.section-heading {
  font-size: 20px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--accent-color);
}

.executive-summary {
  background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--white) 100%);
}

.executive-summary p {
  font-size: 16px;
  line-height: 1.8;
  color: var(--text-secondary);
}

.key-points-list {
  list-style: none;
}

.key-points-list li {
  padding: 12px 0;
  border-bottom: 1px solid var(--border-color);
  font-size: 15px;
  color: var(--text-secondary);
  display: flex;
  align-items: flex-start;
  gap: 12px;
}

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

.key-points-list li::before {
  content: "✓";
  color: var(--accent-color);
  font-weight: 700;
  flex-shrink: 0;
}

.key-points-list strong {
  color: var(--text-primary);
}

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

.toc-list li {
  padding: 12px 0;
  border-bottom: 1px solid var(--border-color);
  font-size: 15px;
}

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

.toc-list li::before {
  counter-increment: toc;
  content: counter(toc) ".";
  color: var(--accent-color);
  font-weight: 600;
  margin-right: 12px;
}

.download-section {
  text-align: center;
}

.download-section .btn {
  margin: 0 8px 8px;
}

/* Related Cards Grid */
.related-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.related-card {
  background: var(--white);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  transition: all 0.2s;
}

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

.related-card-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.related-card-meta {
  font-size: 12px;
  color: var(--text-muted);
}

/* Sidebar Layout */
.sidebar-layout {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 40px;
}

.sidebar {
  background: var(--white);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 24px;
}

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

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

.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: 14px;
  color: var(--text-secondary);
  display: block;
}

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

/* 404 Page */
.error-page {
  min-height: calc(100vh - var(--header-height) - 200px);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 64px 24px;
}

.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: 24px;
  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;
}

/* Footer */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 48px 24px 24px;
  margin-top: 64px;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
}

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

.footer-brand {
  font-size: 18px;
  font-weight: 700;
  color: var(--accent-color);
  margin-bottom: 12px;
}

.footer-desc {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.7;
}

.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 {
  border-top: 1px solid var(--border-color);
  padding-top: 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

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

.footer-nav {
  display: flex;
  gap: 24px;
}

.footer-nav a {
  font-size: 13px;
  color: var(--text-muted);
}

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

/* Responsive Design */
@media (max-width: 1024px) {
  .three-col {
    grid-template-columns: repeat(2, 1fr);
  }

  .sidebar-layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    order: 2;
  }

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

@media (max-width: 768px) {
  .header-inner {
    flex-wrap: wrap;
    height: auto;
    padding: 12px 16px;
    gap: 12px;
  }

  .nav {
    order: 3;
    width: 100%;
    gap: 16px;
    justify-content: center;
    padding-top: 8px;
    border-top: 1px solid var(--border-color);
  }

  .search-box {
    order: 2;
  }

  .search-box input {
    width: 160px;
  }

  .hero {
    padding: 40px 16px;
  }

  .hero-title {
    font-size: 24px;
  }

  .hero-subtitle {
    font-size: 14px;
  }

  .categories {
    gap: 8px;
  }

  .category-tag {
    padding: 8px 16px;
    font-size: 13px;
  }

  .container {
    padding: 24px 16px;
  }

  .three-col {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .card-header {
    flex-direction: column;
    gap: 8px;
  }

  .card-actions {
    flex-wrap: wrap;
  }

  .article-title {
    font-size: 24px;
  }

  .content-section {
    padding: 20px;
  }

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

  .footer-top {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }

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

@media (max-width: 480px) {
  .hero-title {
    font-size: 20px;
  }

  .section-title {
    font-size: 20px;
  }

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

  .btn {
    padding: 8px 16px;
    font-size: 13px;
  }
}