/* Converting all Tailwind classes to traditional CSS */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  
  html {
    height: 100%;
  }

  body {
    font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    line-height: 1.6;
    color: #374151;
    background-color: #f9fafb;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    /* 仅给悬浮底栏留空，高度由 JS 同步 */
    padding-bottom: var(--footer-offset, 4.5rem);
  }
  
  /* Header Styles */
  .header {
    background: white;
    border-bottom: 1px solid #e5e7eb;
    position: sticky;
    top: 0;
    z-index: 50;
  }
  
  .header-container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 1rem;
  }
  
  .header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 4rem;
  }
  
  .logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }
  
  .logo-icon {
    width: 2rem;
    height: 2rem;
    background: linear-gradient(135deg, #1ca699, #dff5ff);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: bold;
    font-size: 0.875rem;
  }
  
  .logo-text {
    font-size: 1.25rem;
    font-weight: bold;
    color: #111827;
  }
  
  .logo-subtitle {
    font-size: 0.875rem;
    color: #6b7280;
    display: none;
  }
  
  @media (min-width: 768px) {
    .logo-subtitle {
      display: block;
    }
  }
  
  .nav-desktop {
    display: none;
    align-items: center;
    gap: 2rem;
  }
  
  @media (min-width: 768px) {
    .nav-desktop {
      display: flex;
    }
  }
  
  .nav-link {
    color: #374151;
    text-decoration: none;
    transition: color 0.2s;
  }
  
  .nav-link:hover {
    color: #f97316;
  }
  
  .header-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
  }
  
  .icon-btn {
    background: none;
    border: none;
    padding: 0.5rem;
    border-radius: 0.375rem;
    cursor: pointer;
    color: #6b7280;
    transition: background-color 0.2s;
    display: none;
  }
  
  @media (min-width: 768px) {
    .icon-btn {
      display: flex;
    }
  }
  
  .icon-btn:hover {
    background-color: #f3f4f6;
  }
  
  .mobile-menu-btn {
    background: none;
    border: none;
    padding: 0.5rem;
    border-radius: 0.375rem;
    cursor: pointer;
    color: #6b7280;
    display: flex;
  }
  
  @media (min-width: 768px) {
    .mobile-menu-btn {
      display: none;
    }
  }
  
  /* Main Content Layout */
  .main-content {
    display: flex;
    flex: 1 0 auto;
    width: 100%;
    max-width: 1280px;
    margin: 0 auto;
  }
  
  .sidebar-left {
    width: 16rem;
    background: white;
    box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    border-right: 1px solid #e5e7eb;
    align-self: stretch;
  }
  
  .main-center {
    flex: 1;
    padding: 1.5rem;
  }
  
  .sidebar-right {
    width: 20rem;
    background: white;
    box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    border-left: 1px solid #e5e7eb;
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
  }
  
  /* Categories Section */
  .categories-section {
    padding: 1.5rem;
  }
  
  .section-header {
    margin-bottom: 1.5rem;
  }
  
  .section-header h2 {
    font-size: 1.125rem;
    font-weight: 600;
    color: #111827;
    margin-bottom: 0.5rem;
  }
  
  .section-header p {
    font-size: 0.875rem;
    color: #6b7280;
  }
  
  .categories-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
  }
  
  .category-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.2s;
  }
  
  .category-item:hover {
    background-color: #f9fafb;
  }
  
  .category-content {
    display: flex;
    align-items: center;
    gap: 0.75rem;
  }
  
  .category-icon {
    padding: 0.5rem;
    border-radius: 0.5rem;
    transition: transform 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
  }
  
  .category-icon i {
    font-size: 16px;
    color: white;
  }
  
  .category-item:hover .category-icon {
    transform: scale(1.1);
  }
  
  .category-icon.blue {
    background-color: #dbeafe;
    color: #2563eb;
  }
  
  .category-icon.green {
    background-color: #dcfce7;
    color: #16a34a;
  }
  
  .category-icon.purple {
    background-color: #e9d5ff;
    color: #9333ea;
  }
  
  .category-icon.orange {
    background-color: #fed7aa;
    color: #ea580c;
  }
  
  .category-icon.red {
    background-color: #fecaca;
    color: #dc2626;
  }
  
  .category-icon.indigo {
    background-color: #e0e7ff;
    color: #4f46e5;
  }
  
  .category-icon.yellow {
    background-color: #fef3c7;
    color: #d97706;
  }
  
  .category-icon.pink {
    background-color: #fce7f3;
    color: #ec4899;
  }
  
  .category-content span {
    font-size: 0.875rem;
    font-weight: 500;
    color: #374151;
    transition: color 0.2s;
  }
  
  .category-item:hover .category-content span {
    color: #111827;
  }
  
  .category-count {
    font-size: 0.75rem;
    background-color: #f3f4f6;
    color: #6b7280;
    padding: 0.25rem 0.5rem;
    border-radius: 9999px;
    transition: background-color 0.2s;
  }
  
  .category-item:hover .category-count {
    background-color: #e5e7eb;
  }
  
  /* Statistics Section */
  .stats-section {
    margin-top: 2rem;
    padding: 1rem;
    background: linear-gradient(135deg, #f9fafb, #f3f4f6);
    border-radius: 0.5rem;
    border: 1px solid #e5e7eb;
  }
  
  .stats-section h3 {
    font-size: 0.875rem;
    font-weight: 600;
    color: #374151;
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }
  
  .stats-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
  }
  
  .stat-item {
    text-align: center;
    padding: 1rem;
    background: rgba(255, 255, 255, 0.8);
    border-radius: 12px;
    border: 1px solid rgba(0, 0, 0, 0.05);
    transition: all 0.2s ease;
  }
  
  .stat-item:hover {
    background: rgba(255, 255, 255, 0.95);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  }
  
  .stat-number {
    font-size: 2rem;
    font-weight: 700;
    color: #1f2937;
    margin-bottom: 0.25rem;
    line-height: 1.2;
  }
  
  .stat-label {
    font-size: 0.875rem;
    color: #6b7280;
    font-weight: 500;
  }
  
  /* Showcase Section */
  .showcase-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
  }
  
  .showcase-section .section-header h2 {
    font-size: 1.5rem;
    font-weight: bold;
    color: #111827;
    margin-bottom: 0.5rem;
  }
  
  .showcase-section .section-header p {
    color: #6b7280;
  }
  
  .articles-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 24px;
  }
  
  @media (max-width: 768px) {
    .articles-list {
      grid-template-columns: 1fr;
      gap: 16px;
    }
    
    .article-card {
      border-radius: 12px;
    }
    
    .article-content {
      padding: 16px;
    }
    
    .article-header h3 {
      font-size: 1.25rem;
    }
  }
  
  .article-card {
    background: white;
    border-radius: 16px;
    border: 1px solid #e5e7eb;
    overflow: hidden;
    transition: all 0.3s ease;
    position: relative;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
  }
  
  .article-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.12);
    border-color: #d1d5db;
  }

  .article-category-badge {
    position: absolute;
    top: 16px;
    right: 16px;
    background: #007aff;
    color: white;
    padding: 6px 16px;
    border-radius: 20px;
    font-size: 12px;
    font-weight: 600;
    box-shadow: 0 2px 8px rgba(0, 122, 255, 0.3);
    z-index: 2;
    pointer-events: none;
  }
  
  .article-card > div {
    display: flex;
    flex-direction: column;
  }
  
  .article-image {
    width: 100%;
    height: 200px;
    flex-shrink: 0;
    position: relative;
    overflow: hidden;
  }
  
  .article-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.3s ease;
  }
  
  .article-card:hover .article-image img {
    transform: scale(1.05);
  }
  
  .article-content {
    flex: 1;
    padding: 24px;
  }
  
  .article-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    margin-bottom: 12px;
  }
  
  .article-cover-link {
    display: block;
    width: 100%;
    height: 100%;
  }

  .article-header h3 {
    font-size: 1.5rem;
    font-weight: 700;
    color: #1d1d1f;
    overflow: hidden;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    line-height: 1.3;
    margin: 0;
  }

  .article-header h3 a {
    color: inherit;
    text-decoration: none;
    transition: color 0.2s;
  }
  
  .article-header h3 a:hover {
    color: #007aff;
  }
  
  .article-category {
    font-size: 0.75rem;
    background-color: #dbeafe;
    color: #2563eb;
    border: 1px solid #bfdbfe;
    padding: 0.25rem 0.5rem;
    border-radius: 0.25rem;
  }
  
  .article-description {
    color: #86868b;
    font-size: 15px;
    margin-bottom: 16px;
    overflow: hidden;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    line-height: 1.6;
  }
  
  .article-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 16px;
  }
  
  .tag {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    font-size: 12px;
    background-color: #f5f5f7;
    color: #86868b;
    padding: 4px 12px;
    border-radius: 12px;
    font-weight: 500;
  }

  .tag i {
    font-size: 14px;
    line-height: 1;
  }
  
  .article-meta {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 13px;
    color: #86868b;
    margin-top: 16px;
  }
  
  .meta-info {
    display: flex;
    align-items: center;
    gap: 16px;
  }
  
  .meta-item {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 13px;
  }
  
  .read-more-btn {
    background: none;
    border: none;
    color: #007aff;
    cursor: pointer;
    font-size: 13px;
    padding: 0;
    font-weight: 500;
    text-decoration: none;
    transition: color 0.2s ease;
    transition: color 0.2s;
  }
  
  .read-more-btn:hover {
    color: #1d4ed8;
  }
  
  .load-more {
    text-align: center;
    padding: 32px 0;
  }
  
  .load-more-btn {
    background: #007aff;
    border: none;
    color: white;
    padding: 12px 32px;
    border-radius: 25px;
    cursor: pointer;
    font-weight: 600;
    font-size: 14px;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(0, 122, 255, 0.3);
  }
  
  .load-more-btn:hover {
    background: #0056b3;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 122, 255, 0.4);
  }
  
  /* Profile Card */
  .profile-card {
    background: white;
    border-radius: 0.5rem;
    border: 1px solid #e5e7eb;
    padding: 1.5rem;
    box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  }
  
  .profile-header {
    text-align: center;
    margin-bottom: 1.5rem;
  }
  
  .profile-avatar {
    width: 8rem;
    height: 8rem;
    background: transparent;
    border-radius: 50%;
    margin: 0 auto 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    color: inherit;
    font-weight: bold;
    font-size: 1.5rem;
    padding: 0;
    overflow: hidden;
  }

  .profile-avatar img {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    display: block;
    object-fit: cover;
  }
  
  .profile-header h2 {
    font-size: 1.25rem;
    font-weight: bold;
    color: #111827;
    margin-bottom: 0.25rem;
  }
  
  .profile-title {
    font-size: 0.875rem;
    color: #6b7280;
    margin-bottom: 0.75rem;
  }
  
  .profile-location,
  .profile-experience {
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    color: #6b7280;
    gap: 0.25rem;
    margin-bottom: 0.5rem;
  }
  
  .profile-contact {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
  }
  
  .contact-item {
    display: flex;
    align-items: center;
    font-size: 0.875rem;
    color: #6b7280;
    cursor: pointer;
    transition: color 0.2s;
    gap: 0.75rem;
  }
  
  .contact-item:hover {
    color: #f97316;
  }
  
  .contact-item span {
    flex: 1;
  }
  
  .profile-skills {
    border-top: 1px solid #f3f4f6;
    padding-top: 1rem;
  }
  
  .profile-skills h3 {
    font-size: 0.875rem;
    font-weight: 600;
    color: #374151;
    margin-bottom: 0.75rem;
  }
  
  .skills-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
  }
  
  .skill-item {
    display: block;
    padding: 16px 20px;
    border-radius: 12px;
    background: #f5f7fb;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    text-align: left;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
  }
  
  .skill-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 16px rgba(0,0,0,0.15);
  }
  
  /* 动态样式通过内联样式设置 */
  
  .skill-name {
    display: block;
    font-weight: 700;
    font-size: 18px;
    line-height: 22px;
    color: #1f2937;
    margin-bottom: 6px;
  }
  
  .skill-desc {
    display: block;
    color: #6b7280;
    font-size: 13px;
    line-height: 18px;
  }
  
  /* 动态颜色通过内联样式设置 */
  
  /* Skills Section */
  .skills-section {
    background: white;
    border-radius: 0.5rem;
    border: 1px solid #e5e7eb;
    padding: 1.5rem;
    box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  }
  
  .skills-section h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: #111827;
    margin-bottom: 1rem;
  }
  
  .skill-category {
    margin-bottom: 1rem;
  }
  
  .skill-category h4 {
    font-size: 0.875rem;
    font-weight: 500;
    color: #374151;
    margin-bottom: 0.5rem;
  }
  
  .skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
  }
  
  .skill-tag-group {
    display: flex;
    align-items: center;
    gap: 0.25rem;
  }
  
  .skill-tag {
    font-size: 0.75rem;
    background: white;
    border: 1px solid #d1d5db;
    padding: 0.25rem 0.5rem;
    border-radius: 0.25rem;
  }
  
  .skill-level {
    font-size: 0.75rem;
    padding: 0.25rem 0.5rem;
    border-radius: 0.25rem;
  }
  
  .skill-level.expert {
    background-color: #dcfce7;
    color: #166534;
    border: 1px solid #bbf7d0;
  }
  
  .skill-level.advanced {
    background-color: #dbeafe;
    color: #1e40af;
    border: 1px solid #bfdbfe;
  }
  
  .skill-level.intermediate {
    background-color: #fef3c7;
    color: #92400e;
    border: 1px solid #fde68a;
  }
  
  /* Friends Section */
  .friends-section {
    background: white;
    border-radius: 0.5rem;
    border: 1px solid #e5e7eb;
    padding: 1.5rem;
    box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  }
  
  .friends-section h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: #111827;
    margin-bottom: 1rem;
  }
  
  .friends-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
  }
  
  .friend-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem;
    background-color: #f9fafb;
    border-radius: 0.5rem;
    transition: background-color 0.2s;
  }
  
  .friend-item:hover {
    background-color: #f3f4f6;
  }

  a.friend-item {
    text-decoration: none;
    color: inherit;
  }
  
  .friend-content {
    display: flex;
    align-items: center;
    gap: 0.75rem;
  }
  
  .friend-icon {
    width: 2rem;
    height: 2rem;
    background-color: #dbeafe;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #2563eb;
  }
  
  .friend-info h4 {
    font-size: 0.875rem;
    font-weight: 500;
    color: #111827;
  }
  
  .friend-info p {
    font-size: 0.75rem;
    color: #6b7280;
  }
  
  .friend-link-btn {
    background: none;
    border: none;
    padding: 0.25rem;
    cursor: pointer;
    color: #6b7280;
  }
  
  .apply-friend-link {
    margin-top: 1rem;
    padding: 0.75rem;
    background-color: #dbeafe;
    border-radius: 0.5rem;
    text-align: center;
  }
  
  .apply-friend-link p {
    font-size: 0.75rem;
    color: #2563eb;
    margin-bottom: 0.5rem;
  }
  
  .apply-btn {
    background: transparent;
    border: 1px solid #2563eb;
    color: #2563eb;
    padding: 0.25rem 0.75rem;
    border-radius: 0.25rem;
    font-size: 0.75rem;
    cursor: pointer;
    transition: all 0.2s;
    display: inline-block;
    text-decoration: none;
  }
  
  .apply-btn:hover {
    background-color: #2563eb;
    color: white;
  }
  
  /* Footer：主体随页面滚动 */
  .footer {
    background: white;
    color: #111827;
    border-top: 1px solid #e5e7eb;
    flex-shrink: 0;
    width: 100%;
  }
  
  .footer-container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 3rem 1rem;
  }
  
  .footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
  }
  
  @media (min-width: 768px) {
    .footer-content {
      grid-template-columns: repeat(4, 1fr);
    }
  }
  
  .footer-brand {
    display: flex;
    flex-direction: column;
    gap: 1rem;
  }
  
  .footer-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }
  
  .footer-brand p {
    color: #6b7280;
    font-size: 0.875rem;
    line-height: 1.6;
  }
  
  .footer-section h4 {
    font-weight: 600;
    color: #111827;
    margin-bottom: 1rem;
  }
  
  .footer-links {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
  }
  
  .footer-links a {
    color: #6b7280;
    text-decoration: none;
    font-size: 0.875rem;
    transition: color 0.2s;
  }
  
  .footer-links a:hover {
    color: #f97316;
  }
  
  .footer-social {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
  }
  
  .social-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2rem;
    height: 2rem;
    background: none;
    border: none;
    padding: 0;
    border-radius: 0.375rem;
    cursor: pointer;
    color: #6b7280;
    transition: color 0.2s;
    line-height: 1;
    text-decoration: none;
    flex-shrink: 0;
  }

  .social-btn svg,
  .social-btn i {
    width: 1rem;
    height: 1rem;
    font-size: 1rem;
    line-height: 1;
    display: block;
  }
  
  .social-btn:hover {
    color: #f97316;
  }
  
  .footer-email,
  .footer-contact-info p {
    color: #6b7280;
    font-size: 0.875rem;
    line-height: 1.6;
  }
  
  /* 版权 + 备案：固定悬浮在视口底部 */
  .footer-bottom {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 40;
    margin-top: 0;
    padding: 0.75rem 1rem;
    border-top: 1px solid #e5e7eb;
    text-align: center;
    background: white;
    box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.06);
  }
  
  .footer-bottom p {
    font-size: 0.875rem;
    color: #6b7280;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.25rem;
    flex-wrap: wrap;
  }
  
  .footer-bottom svg {
    color: #ef4444;
  }

  .footer-beian {
    margin-top: 0.25rem;
  }

  .footer-beian a {
    color: #6b7280;
    text-decoration: none;
    font-size: 0.8125rem;
  }

  .footer-beian a:hover {
    color: #374151;
    text-decoration: underline;
  }
  
  /* Responsive Design */
  @media (max-width: 1024px) {
    .main-content {
      flex-direction: column;
    }
  
    .sidebar-left,
    .sidebar-right {
      width: 100%;
    }
  
    .sidebar-left {
      order: 2;
    }
  
    .main-center {
      order: 1;
    }
  
    .sidebar-right {
      order: 3;
      padding: 1.5rem;
    }
  }
  
  @media (max-width: 768px) {
    .article-card > div {
      flex-direction: column;
    }
  
    .article-image {
      width: 100%;
      height: 12rem;
    }
  
    .skills-grid {
      grid-template-columns: 1fr;
    }
  }