:root {
      --bg-primary: #ffffff;
      --bg-secondary: #f7f8fa;
      --bg-card: #ffffff;
      --bg-card-hover: #f5f6f8;
      --border: #e5e7eb;
      --text-primary: #1a1a2e;
      --text-secondary: #6b7280;
      --text-muted: #9ca3af;
      --accent: #6366f1;
      --accent-light: #818cf8;
      --accent-bg: rgba(99, 102, 241, 0.08);
      --success: #22c55e;
      --warning: #f59e0b;
      --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.06);
      --shadow-lg: 0 10px 25px rgba(0,0,0,0.08);
      --radius: 12px;
      --radius-sm: 8px;
    }

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

    body {
      font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
      background: var(--bg-primary);
      color: var(--text-primary);
      line-height: 1.6;
      min-height: 100vh;
    }

    .mono { font-family: 'JetBrains Mono', monospace; }

    /* Header */
    header {
      position: fixed;
      top: 0;
      left: 0;
      right: 0;
      height: 64px;
      background: rgba(255, 255, 255, 0.95);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--border);
      z-index: 100;
      display: flex;
      align-items: center;
      justify-content: space-between;
      max-width: 900px;
      margin: 0 auto;
      padding: 0 24px;
    }

    .header-left { display: flex; align-items: center; }

    .logo {
      display: flex;
      align-items: center;
      gap: 10px;
      font-weight: 700;
      font-size: 18px;
      color: var(--text-primary);
      text-decoration: none;
    }

    .logo-icon {
      width: 32px;
      height: 32px;
      background: linear-gradient(135deg, var(--accent), var(--accent-light));
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
      font-size: 14px;
      color: white;
    }

    nav {
      display: flex;
      align-items: center;
      gap: 8px;
    }

    nav a {
      color: var(--text-secondary);
      text-decoration: none;
      padding: 8px 16px;
      border-radius: var(--radius-sm);
      font-size: 14px;
      font-weight: 500;
      transition: all 0.2s;
    }

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

    .menu-toggle {
      display: none;
      flex-direction: column;
      justify-content: space-between;
      width: 24px;
      height: 18px;
      background: none;
      border: none;
      cursor: pointer;
      padding: 0;
    }

    .menu-toggle span {
      display: block;
      width: 100%;
      height: 2px;
      background: var(--text-primary);
      border-radius: 2px;
      transition: all 0.3s;
    }

    .mobile-nav {
      display: none;
      position: fixed;
      top: 64px;
      left: 0;
      right: 0;
      background: white;
      border-bottom: 1px solid var(--border);
      padding: 16px 24px;
      flex-direction: column;
      gap: 8px;
      box-shadow: var(--shadow-lg);
    }

    .mobile-nav.active { display: flex; }

    .mobile-nav a {
      color: var(--text-secondary);
      text-decoration: none;
      padding: 12px 16px;
      border-radius: var(--radius-sm);
      font-size: 15px;
      font-weight: 500;
      transition: all 0.2s;
    }

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

    main { padding-top: 64px; }
    .container { 
          max-width: 900px; 
          margin: 30px auto; 
          padding: 0 24px; 
    }

    /* Hero - Geek Blog Style */
    .hero {
      padding: 30px 0 10px;
    }

    .hero-code {
      font-family: 'JetBrains Mono', monospace;
      font-size: 14px;
      color: var(--accent);
      margin-bottom: 20px;
    }

    .hero-code .keyword { color: #c678dd; }
    .hero-code .string { color: #98c379; }
    .hero-code .comment { color: var(--text-muted); }

    .hero h1 {
      font-size: 48px;
      font-weight: 700;
      letter-spacing: -0.02em;
      margin-bottom: 8px;
      color: var(--text-primary);
    }

    .hero-subtitle {
      font-size: 18px;
      color: var(--text-secondary);
      margin-bottom: 32px;
    }

    .hero-tags {
      display: flex;
      flex-wrap: wrap;
      gap: 10px;
      margin-bottom: 32px;
    }

    .hero-tag {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      padding: 6px 14px;
      background: var(--bg-secondary);
      border: 1px solid var(--border);
      border-radius: 20px;
      font-size: 13px;
      color: var(--text-secondary);
      font-weight: 500;
      transition: all 0.2s;
    }

    .hero-tag:hover {
      border-color: var(--accent);
      color: var(--accent);
      background: var(--accent-bg);
    }

    .hero-tag .icon { font-size: 14px; }

    /* Section */
    .section { margin: 10px 0; }
    .section-title {
      font-size: 24px;
      font-weight: 600;
      margin-bottom: 24px;
      display: flex;
      align-items: center;
      gap: 10px;
    }

    .section-title::before {
      content: '';
      width: 4px;
      height: 24px;
      background: var(--accent);
      border-radius: 2px;
    }

    /* Post list */
    .post-list { display: flex; flex-direction: column; gap: 16px; }

    .post-card {
      display: block;
      padding: 20px 24px;
      background: var(--bg-card);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      text-decoration: none;
      color: var(--text-primary);
      transition: all 0.2s;
      box-shadow: var(--shadow);
    }

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

    .post-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 8px;
    }

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

    .post-date {
      font-size: 13px;
      color: var(--text-muted);
      font-family: 'JetBrains Mono', monospace;
    }

    .post-desc {
      font-size: 14px;
      color: var(--text-secondary);
      margin-bottom: 12px;
    }

    .post-tags {
      display: flex;
      gap: 8px;
      flex-wrap: wrap;
    }

    .post-tag {
      padding: 4px 10px;
      background: var(--accent-bg);
      border-radius: 4px;
      font-size: 12px;
      color: var(--accent);
      font-weight: 500;
    }

    .post-tag.tag-dl { background: rgba(239, 68, 68, 0.08); color: #ef4444; }
    .post-tag.tag-recsys { background: rgba(245, 158, 11, 0.08); color: #f59e0b; }
    .post-tag.tag-llm { background: rgba(34, 197, 94, 0.08); color: #22c55e; }
    .post-tag.tag-agent { background: rgba(99, 102, 241, 0.08); color: #6366f1; }

    /* Category cards */
    .category-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 16px;
    }

    .category-card {
      display: flex;
      flex-direction: column;
      align-items: center;
      padding: 24px 16px;
      background: var(--bg-card);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      text-decoration: none;
      color: var(--text-primary);
      transition: all 0.2s;
      box-shadow: var(--shadow);
      text-align: center;
    }

    .category-card:hover {
      box-shadow: var(--shadow-lg);
      border-color: var(--accent);
      transform: translateY(-2px);
    }

    .category-icon {
      width: 48px;
      height: 48px;
      border-radius: 12px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 24px;
      margin-bottom: 12px;
    }

    .category-card:nth-child(1) .category-icon { background: rgba(239, 68, 68, 0.1); }
    .category-card:nth-child(2) .category-icon { background: rgba(245, 158, 11, 0.1); }
    .category-card:nth-child(3) .category-icon { background: rgba(34, 197, 94, 0.1); }
    .category-card:nth-child(4) .category-icon { background: rgba(99, 102, 241, 0.1); }

    .category-name {
      font-size: 15px;
      font-weight: 600;
      margin-bottom: 4px;
    }

    .category-desc {
      font-size: 12px;
      color: var(--text-muted);
    }

    /* Article list */
    .article-list { 
        display: flex; 
        flex-direction: column; 
        gap: 24px; 
        margin: 40px 0; 
    }
    .article-card {
      display: block;
      padding: 28px 32px;
      background: var(--bg-card);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      text-decoration: none;
      color: var(--text-primary);
      transition: all 0.2s;
      box-shadow: var(--shadow);
    }
    .article-card:hover {
      box-shadow: var(--shadow-lg);
      border-color: var(--accent);
      transform: translateY(-2px);
    }
    .article-header { 
        display: flex; 
        align-items: flex-start; 
        justify-content: space-between; 
        margin-bottom: 12px; 
        gap: 16px; 
    }
    .article-title { 
        font-size: 18px; 
        font-weight: 600; 
        color: var(--text-primary); 
        line-height: 1.4; 
    }
    .article-date { 
        font-size: 13px; 
        color: var(--text-muted); 
        font-family: 'JetBrains Mono', 
        monospace; white-space: nowrap; 
    }
    .article-desc { 
        font-size: 14px; 
        color: var(--text-secondary); 
        margin-bottom: 16px; 
        line-height: 1.6; 
    }
    .article-tags { 
        display: flex; 
        gap: 8px; 
        flex-wrap: wrap; 
    }
    .article-tag {
      padding: 4px 12px;
      background: var(--accent-bg);
      border-radius: 4px;
      font-size: 12px;
      color: var(--accent);
      font-weight: 500;
    }

    img { 
          max-width: 100%; 
          object-fit: cover; 
          border-radius: 10px; 
    }
    h1 {
        margin-top: 2rem;
        margin-bottom: 1rem;
        font-weight: normal;
        color: #159957;
        font-size: 1.5em
    }

    h2 {
        margin-top: 2rem;
        margin-bottom: 1rem;
        font-weight: normal;
        color: #159957;
        font-size: 1.3em;
    }

    h3 {
        margin-top: 2rem;
        margin-bottom: 1rem;
        font-weight: normal;
        font-size: 1.2em
    }

    h4, h5, h6 {
        margin-top: 2rem;
        margin-bottom: 1rem;
        font-weight: normal;
        font-size: 1em;
    }


    table {
      width: 100%;
      border-collapse: collapse;
      background: var(--bg-card);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      overflow: hidden;
      box-shadow: var(--shadow);
    }

    th, td {
      padding: 14px 20px;
      text-align: left;
      font-size: 14px;
      border-bottom: 1px solid var(--border);
    }

    th {
      background: var(--bg-secondary);
      font-weight: 600;
      color: var(--text-secondary);
      font-size: 12px;
      text-transform: uppercase;
      letter-spacing: 0.05em;
    }

    td {
      color: var(--text-primary);
    }

    tr:last-child td {
      border-bottom: none;
    }

    tr:hover td {
      background: var(--bg-card-hover);
    }

    /* Footer */
    footer {
      background: var(--bg-secondary);
      border-top: 1px solid var(--border);
      padding: 10px 0;
      margin-top: 80px;
    }

    .footer-content {
      display: flex;
      justify-content: center;
      align-items: center;
    }

    .footer-copy { font-size: 18px; color: var(--text-muted); text-align: center; }

    /* Responsive */
    @media (max-width: 768px) {
      .hero h1 { font-size: 32px; }
      .hero-subtitle { font-size: 16px; }
      .category-grid { grid-template-columns: repeat(2, 1fr); }
      nav { display: none; }
      .menu-toggle { display: flex; }
    }