:root {
      --kmitl-orange: #E65525;
      --kmitl-orange-light: #F0764D;
      --kmitl-orange-dark: #C44319;
      --navy-900: #0F172A;
      --navy-800: #1E293B;
      --navy-700: #334155;
      --gray-50: #F8FAFC;
      --gray-100: #F1F5F9;
      --gray-200: #E2E8F0;
      --gray-300: #CBD5E1;
      --gray-500: #64748B;
      
      --bg: var(--gray-50);
      --card-bg: #FFFFFF;
      --text-main: var(--navy-800);
      --text-muted: var(--gray-500);
      --border: var(--gray-200);
      
      --radius: 8px;
      --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
      --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    }

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

    body {
      font-family: 'Sarabun', sans-serif;
      background: var(--bg);
      color: var(--text-main);
      min-height: 100vh;
      line-height: 1.5;
    }

    h1, h2, h3, h4, h5, h6, .font-prompt {
      font-family: 'Prompt', sans-serif;
    }

    .container { max-width: 1024px; margin: 0 auto; padding: 0 24px 40px; }

    header {
      background-color: var(--card-bg);
      border-bottom: 2px solid var(--kmitl-orange);
      padding: 24px 0;
      margin-bottom: 40px;
      box-shadow: var(--shadow-sm);
    }
    .header-content {
      max-width: 1024px;
      margin: 0 auto;
      padding: 0 24px;
      display: flex;
      align-items: center;
      gap: 16px;
    }
    .logo-box {
      width: 56px;
      height: 56px;
      background-color: var(--kmitl-orange);
      color: white;
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 28px;
      font-weight: bold;
      font-family: 'Prompt', sans-serif;
    }
    .header-text h1 {
      font-size: 20px;
      color: var(--navy-900);
      margin-bottom: 4px;
    }
    .header-text p {
      font-size: 14px;
      color: var(--text-muted);
      font-family: 'Sarabun', sans-serif;
    }

    .back-link {
      display: inline-flex; align-items: center; gap: 8px;
      margin-bottom: 24px; font-size: 15px; color: var(--navy-700);
      text-decoration: none; font-weight: 500; font-family: 'Prompt', sans-serif;
      transition: color 0.2s;
    }
    .back-link:hover { color: var(--kmitl-orange); }

    .card {
      background: var(--card-bg);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      padding: 32px;
      margin-bottom: 24px;
      box-shadow: var(--shadow-sm);
    }
    .card-title {
      font-family: 'Prompt', sans-serif;
      font-size: 18px;
      font-weight: 600;
      color: var(--navy-900);
      margin-bottom: 24px;
      display: flex;
      align-items: center;
      gap: 12px;
      padding-bottom: 12px;
      border-bottom: 1px solid var(--gray-100);
    }

    /* Filter & Search */
    .filter-bar {
      display: flex;
      gap: 16px;
      margin-bottom: 24px;
      flex-wrap: wrap;
    }
    .search-input {
      flex: 1;
      min-width: 250px;
      padding: 12px 16px;
      border: 1px solid var(--gray-300);
      border-radius: 6px;
      font-family: 'Sarabun', sans-serif;
      font-size: 15px;
      color: var(--navy-900);
      transition: border-color 0.2s;
    }
    .search-input:focus {
      outline: none;
      border-color: var(--kmitl-orange);
      box-shadow: 0 0 0 2px rgba(230,85,37,0.1);
    }
    .category-select {
      padding: 12px 16px;
      border: 1px solid var(--gray-300);
      border-radius: 6px;
      font-family: 'Sarabun', sans-serif;
      font-size: 15px;
      color: var(--navy-900);
      background-color: white;
      min-width: 200px;
      cursor: pointer;
    }
    
    /* Courses List */
    .table-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius); }
    table { width: 100%; border-collapse: collapse; font-size: 14px; }
    thead { background: var(--gray-50); border-bottom: 2px solid var(--gray-200); }
    th {
      padding: 12px 16px; text-align: left; font-size: 14px; font-family: 'Prompt', sans-serif;
      color: var(--navy-700); font-weight: 600; white-space: nowrap;
    }
    td { padding: 12px 16px; border-bottom: 1px solid var(--border); vertical-align: middle; }
    tbody tr:last-child td { border-bottom: none; }
    tbody tr:hover { background-color: var(--gray-50); }

    .badge {
      display: inline-block; font-size: 12px; font-weight: 500; font-family: 'Prompt', sans-serif;
      padding: 4px 8px; border-radius: 4px;
    }
    .badge-ge { background: #E2E8F0; color: #334155; }
    .badge-core-math { background: #E0F2FE; color: #0284C7; }
    .badge-core-cs { background: #FFF7F5; color: #E65525; }
    .badge-elective { background: #FEF3C7; color: #D97706; }
    .badge-free { background: #FCE7F3; color: #DB2777; }
    .badge-alt { background: #EDE9FE; color: #7C3AED; }

    /* Prerequisite Button & Status */
    .btn-prereq {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      background-color: #FFF7ED;
      color: #C2410C;
      border: 1px solid #FDBA74;
      padding: 5px 12px;
      border-radius: 6px;
      font-family: 'Prompt', sans-serif;
      font-size: 12px;
      font-weight: 500;
      cursor: pointer;
      transition: all 0.2s ease;
      white-space: nowrap;
    }
    .btn-prereq:hover {
      background-color: #FFEDD5;
      border-color: #FB923C;
      color: #9A3412;
      box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    }
    .no-prereq {
      color: var(--gray-500);
      font-size: 13px;
    }

    .loading-box { text-align: center; padding: 48px; color: var(--text-muted); font-family: 'Prompt', sans-serif; }

    /* Prerequisite Modal */
    .modal-overlay {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: rgba(15, 23, 42, 0.6);
      backdrop-filter: blur(2px);
      display: none;
      align-items: center;
      justify-content: center;
      z-index: 1000;
      padding: 16px;
    }
    .modal-overlay.show {
      display: flex;
    }
    .modal-box {
      background: #FFFFFF;
      border-radius: 12px;
      max-width: 620px;
      width: 100%;
      max-height: 90vh;
      overflow-y: auto;
      box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
      border: 1px solid var(--border);
      animation: modalFadeIn 0.2s ease-out;
    }
    @keyframes modalFadeIn {
      from { opacity: 0; transform: translateY(-8px) scale(0.98); }
      to { opacity: 1; transform: translateY(0) scale(1); }
    }
    .modal-header {
      padding: 20px 24px;
      border-bottom: 1px solid var(--gray-200);
      display: flex;
      align-items: center;
      justify-content: space-between;
    }
    .modal-title {
      font-family: 'Prompt', sans-serif;
      font-size: 18px;
      font-weight: 600;
      color: var(--navy-900);
    }
    .modal-close {
      background: transparent;
      border: none;
      font-size: 24px;
      line-height: 1;
      color: var(--gray-500);
      cursor: pointer;
      padding: 4px 8px;
      border-radius: 4px;
      transition: all 0.15s;
    }
    .modal-close:hover {
      background: var(--gray-100);
      color: var(--navy-900);
    }
    .modal-body {
      padding: 24px;
    }
    .target-course-card {
      background: var(--gray-50);
      border: 1px solid var(--gray-200);
      border-radius: 8px;
      padding: 16px;
      margin-bottom: 20px;
    }
    .target-course-code {
      font-family: monospace;
      font-size: 13px;
      color: var(--kmitl-orange-dark);
      font-weight: 600;
      margin-bottom: 4px;
    }
    .target-course-name {
      font-family: 'Prompt', sans-serif;
      font-size: 16px;
      font-weight: 600;
      color: var(--navy-900);
      margin-bottom: 2px;
    }
    .target-course-en {
      font-size: 13px;
      color: var(--gray-500);
      margin-bottom: 10px;
    }
    .target-course-meta {
      display: flex;
      align-items: center;
      gap: 8px;
      flex-wrap: wrap;
    }
    .prereq-section-title {
      font-family: 'Prompt', sans-serif;
      font-size: 15px;
      font-weight: 600;
      color: var(--navy-800);
      margin-bottom: 12px;
      display: flex;
      align-items: center;
      justify-content: space-between;
    }
    .prereq-count-badge {
      font-size: 12px;
      font-weight: 500;
      background: var(--gray-100);
      color: var(--navy-700);
      padding: 2px 8px;
      border-radius: 12px;
    }
    .prereq-item {
      border: 1px solid var(--gray-200);
      border-left: 4px solid var(--kmitl-orange);
      background: #FFFFFF;
      border-radius: 6px;
      padding: 14px 16px;
      margin-bottom: 10px;
      transition: border-color 0.2s;
    }
    .prereq-item:hover {
      border-color: var(--kmitl-orange-light);
    }
    .prereq-item-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 4px;
    }
    .prereq-code {
      font-family: monospace;
      font-weight: 600;
      color: var(--kmitl-orange);
      font-size: 13px;
    }
    .prereq-name-th {
      font-family: 'Prompt', sans-serif;
      font-size: 14px;
      font-weight: 600;
      color: var(--navy-900);
      margin-bottom: 2px;
    }
    .prereq-name-en {
      font-size: 12px;
      color: var(--gray-500);
    }
    .modal-note {
      background: #EFF6FF;
      border: 1px solid #BFDBFE;
      border-radius: 6px;
      padding: 12px 16px;
      font-size: 13px;
      color: #1E40AF;
      margin-top: 16px;
      line-height: 1.5;
    }
    .modal-footer {
      padding: 16px 24px;
      border-top: 1px solid var(--gray-200);
      display: flex;
      justify-content: flex-end;
      background: var(--gray-50);
      border-bottom-left-radius: 12px;
      border-bottom-right-radius: 12px;
    }
    .btn-modal-close {
      padding: 8px 18px;
      border: 1px solid var(--gray-300);
      background: #FFFFFF;
      color: var(--navy-700);
      border-radius: 6px;
      font-family: 'Prompt', sans-serif;
      font-size: 14px;
      font-weight: 500;
      cursor: pointer;
      transition: all 0.15s;
    }
    .btn-modal-close:hover {
      background: var(--gray-100);
      color: var(--navy-900);
    }