/* ========================================
       CSS Variables (Design System)
       ======================================== */
    :root {
      --color-aws-dark: #232F3E;
      --color-aws-orange: #dc7600;
      --color-aws-orange-original: #FF9900;
      --color-aws-orange-hover: #EC7211;
      --color-text-primary: #374151;
      --color-text-secondary: #6B7280;
      --color-text-tertiary: #6f7682;
      --color-text-white: #FFFFFF;
      --color-bg-light: #F9FAFB;
      --color-bg-white: #FFFFFF;
      --color-bg-dark: #1F2937;
      --color-bg-gradient-start: #232F3E;
      --color-bg-gradient-end: #374151;
      --color-border: #909296;
      --color-border-light: #E5E7EB;
      --color-shadow: rgba(0, 0, 0, 0.1);
      --color-success: #10B981;
      --color-warning: #F59E0B;
      --color-error: #EF4444;
      --color-info: #3B82F6;
      --spacing-xs: 5px;
      --spacing-sm: 10px;
      --spacing-md: 15px;
      --spacing-base: 20px;
      --spacing-lg: 25px;
      --spacing-xl: 30px;
      --spacing-2xl: 40px;
      --spacing-3xl: 60px;
      --spacing-4xl: 80px;
      --font-size-xs: 0.75em;
      --font-size-sm: 0.85em;
      --font-size-base: 0.95em;
      --font-size-md: 1em;
      --font-size-lg: 1.2em;
      --font-size-xl: 1.5em;
      --font-size-2xl: 2em;
      --font-size-3xl: 2.5em;
      --font-weight-normal: 400;
      --font-weight-medium: 500;
      --font-weight-semibold: 600;
      --font-weight-bold: 700;
      --line-height-tight: 1.25;
      --line-height-normal: 1.5;
      --line-height-relaxed: 1.75;
      --radius-sm: 6px;
      --radius-md: 8px;
      --radius-base: 10px;
      --radius-lg: 15px;
      --radius-xl: 20px;
      --radius-full: 50%;
      --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.05);
      --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
      --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
      --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.2);
      --shadow-xl: 0 20px 50px rgba(0, 0, 0, 0.3);
      --shadow-focus: 0 0 0 3px rgba(255, 153, 0, 0.3);
      --shadow-orange: 0 4px 12px rgba(255, 153, 0, 0.4);
      --shadow-orange-hover: 0 6px 20px rgba(255, 153, 0, 0.6);
      --header-height: 60px;
      --container-max-width: 1200px;
      --transition-fast: 0.15s ease;
      --transition-base: 0.3s ease;
      --transition-slow: 0.5s ease;
      --z-base: 1;
      --z-sticky: 500;
      --z-scroll-top: 1000;
      --z-progress-bar: 1001;
      --z-header: 1002;
    }

    /* ========================================
       Base & Reset
       ======================================== */
    *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

    body {
      font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
      line-height: var(--line-height-normal);
      color: var(--color-text-primary);
      margin: 0;
      padding: var(--spacing-base);
      padding-top: var(--spacing-4xl);
      background-color: var(--color-bg-light);
      font-size: 20px;
    }

    /* ========================================
       Fixed Navigation Header
       ======================================== */
    .fixed-nav-header {
      position: fixed;
      top: 0;
      left: 0;
      right: 0;
      height: var(--header-height);
      background: linear-gradient(135deg, var(--color-bg-gradient-start) 0%, var(--color-bg-gradient-end) 100%);
      box-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
      z-index: var(--z-header);
      display: flex;
      align-items: center;
    }

    .fixed-nav-container {
      width: 100%;
      max-width: var(--container-max-width);
      margin: 0 auto;
      padding: 0 var(--spacing-xl);
      display: flex;
      align-items: center;
      justify-content: space-between;
    }

    .fixed-nav-logo {
      font-size: 1.3em;
      font-weight: var(--font-weight-bold);
      color: var(--color-aws-orange-original);
      text-decoration: none;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .fixed-nav-links {
      display: flex;
      gap: 25px;
      align-items: center;
    }

    .fixed-nav-links a {
      color: var(--color-text-white);
      text-decoration: none;
      font-weight: var(--font-weight-medium);
      font-size: var(--font-size-base);
      padding: 8px 16px;
      border-radius: var(--radius-sm);
      transition: all var(--transition-base);
      white-space: nowrap;
    }

    .fixed-nav-links a:hover {
      background-color: rgba(255, 153, 0, 0.2);
      color: var(--color-aws-orange-original);
    }

    /* ========================================
       Reading Progress Bar
       ======================================== */
    .reading-progress {
      position: fixed;
      top: var(--header-height);
      left: 0;
      width: 100%;
      height: 4px;
      background-color: var(--color-border-light);
      z-index: var(--z-progress-bar);
    }

    .reading-progress-bar {
      height: 100%;
      background: linear-gradient(90deg, var(--color-aws-orange-original) 0%, var(--color-aws-orange-hover) 100%);
      width: 0%;
      transition: width 0.1s ease;
    }

    /* ========================================
       Container
       ======================================== */
    .container {
      max-width: var(--container-max-width);
      margin: 0 auto;
      padding: var(--spacing-2xl);
      background-color: var(--color-bg-white);
      border-radius: 16px;
      box-shadow: var(--shadow-lg);
    }

    /* ========================================
       Hero Section
       ======================================== */
    .hero {
      background: linear-gradient(135deg, #232F3E 0%, #37475A 50%, #485769 100%);
      color: var(--color-text-white);
      padding: var(--spacing-3xl) var(--spacing-2xl);
      border-radius: var(--radius-xl);
      margin-bottom: var(--spacing-2xl);
      text-align: center;
      position: relative;
      overflow: hidden;
    }

    .hero::before {
      content: '';
      position: absolute;
      top: -50%;
      left: -50%;
      width: 200%;
      height: 200%;
      background: radial-gradient(circle at 30% 70%, rgba(255,153,0,0.1) 0%, transparent 50%);
      pointer-events: none;
    }

    .hero-badge {
      display: inline-block;
      background: rgba(255,153,0,0.2);
      color: var(--color-aws-orange-original);
      padding: 8px 20px;
      border-radius: 30px;
      font-size: 0.85em;
      font-weight: var(--font-weight-semibold);
      margin-bottom: var(--spacing-base);
      border: 1px solid rgba(255,153,0,0.3);
    }

    .hero h1 {
      font-size: 2.2em;
      font-weight: var(--font-weight-bold);
      margin-bottom: var(--spacing-md);
      line-height: var(--line-height-tight);
      color: var(--color-text-white);
    }

    .hero-subtitle {
      font-size: 1.1em;
      color: rgba(255,255,255,0.85);
      max-width: 700px;
      margin: 0 auto;
    }

    /* ========================================
       Key Takeaways
       ======================================== */
    .key-takeaways {
      background: linear-gradient(135deg, #FFF7ED 0%, #FFFBF5 100%);
      border: 2px solid #FDBA74;
      border-radius: var(--radius-lg);
      padding: var(--spacing-xl);
      margin-bottom: var(--spacing-2xl);
    }

    .key-takeaways h2 {
      color: var(--color-aws-orange);
      font-size: 1.4em;
      margin-bottom: var(--spacing-base);
      padding-bottom: var(--spacing-sm);
      border-bottom: 2px solid var(--color-aws-orange);
    }

    .takeaway-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
      gap: var(--spacing-base);
    }

    .takeaway-card {
      background: var(--color-bg-white);
      border-radius: var(--radius-base);
      padding: var(--spacing-base);
      box-shadow: var(--shadow-sm);
      border-left: 4px solid var(--color-aws-orange);
    }

    .takeaway-card .takeaway-num {
      display: inline-block;
      background: var(--color-aws-orange);
      color: var(--color-text-white);
      width: 32px;
      height: 32px;
      border-radius: var(--radius-full);
      text-align: center;
      line-height: 32px;
      font-weight: var(--font-weight-bold);
      font-size: 0.85em;
      margin-bottom: var(--spacing-sm);
    }

    .takeaway-card p {
      font-size: 0.95em;
      line-height: var(--line-height-relaxed);
    }

    /* ========================================
       Section Styles
       ======================================== */
    .section {
      margin-bottom: var(--spacing-2xl);
      background-color: var(--color-bg-light);
      padding: var(--spacing-xl);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-sm);
    }

    .section h2 {
      font-size: 1.5em;
      color: var(--color-text-primary);
      margin-bottom: var(--spacing-base);
      padding-bottom: var(--spacing-sm);
      border-bottom: 2px solid var(--color-aws-orange);
    }

    .section h3 {
      font-size: 1.2em;
      color: var(--color-text-primary);
      margin-bottom: var(--spacing-md);
      margin-top: var(--spacing-base);
    }

    .section p {
      line-height: var(--line-height-relaxed);
      margin-bottom: var(--spacing-md);
    }

    /* ========================================
       Analogy Mapping Table
       ======================================== */
    .analogy-table-wrapper {
      overflow-x: auto;
      margin-bottom: var(--spacing-base);
    }

    .analogy-table {
      width: 100%;
      border-collapse: separate;
      border-spacing: 0;
      border-radius: var(--radius-base);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
    }

    .analogy-table th {
      background: linear-gradient(135deg, var(--color-bg-gradient-start), var(--color-bg-gradient-end));
      color: var(--color-text-white);
      padding: 16px 20px;
      text-align: left;
      font-weight: var(--font-weight-semibold);
      font-size: 0.95em;
    }

    .analogy-table td {
      padding: 14px 20px;
      border-bottom: 1px solid var(--color-border-light);
      background: var(--color-bg-white);
      font-size: 0.95em;
    }

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

    .analogy-table tr:hover td {
      background-color: #FFF7ED;
    }

    .analogy-emoji {
      font-size: 1.3em;
      margin-right: 8px;
    }

    /* ========================================
       Comparison Grid (2-column equal)
       ======================================== */
    .compare-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: var(--spacing-base);
      margin-bottom: var(--spacing-base);
    }

    .compare-card {
      background: var(--color-bg-white);
      border-radius: var(--radius-lg);
      padding: var(--spacing-xl);
      box-shadow: var(--shadow-sm);
      transition: all var(--transition-base);
    }

    .compare-card:hover {
      transform: translateY(-3px);
      box-shadow: var(--shadow-md);
    }

    .compare-card.enabled {
      border-top: 4px solid var(--color-info);
    }

    .compare-card.disabled {
      border-top: 4px solid #8B5CF6;
    }

    .compare-card-header {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-bottom: var(--spacing-md);
    }

    .compare-card-icon {
      width: 48px;
      height: 48px;
      border-radius: var(--radius-full);
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 1.4em;
      flex-shrink: 0;
    }

    .compare-card.enabled .compare-card-icon {
      background: #EEF2FF;
      color: var(--color-info);
    }

    .compare-card.disabled .compare-card-icon {
      background: #F3E8FF;
      color: #8B5CF6;
    }

    .compare-card h3 {
      font-size: 1.15em;
      margin: 0;
      color: var(--color-text-primary);
    }

    .compare-card-subtitle {
      font-size: 0.85em;
      color: var(--color-text-secondary);
    }

    .compare-feature-list {
      list-style: none;
      padding: 0;
      margin: 0;
    }

    .compare-feature-list li {
      padding: 10px 0;
      border-bottom: 1px solid var(--color-border-light);
      font-size: 0.95em;
      line-height: var(--line-height-relaxed);
      display: flex;
      align-items: flex-start;
      gap: 10px;
    }

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

    .compare-feature-list .feature-icon {
      flex-shrink: 0;
      margin-top: 3px;
    }

    /* ========================================
       Detail Cards
       ======================================== */
    .detail-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
      gap: var(--spacing-base);
      margin-bottom: var(--spacing-base);
    }

    .detail-card {
      background: var(--color-bg-white);
      border-radius: var(--radius-lg);
      padding: var(--spacing-base);
      box-shadow: var(--shadow-sm);
      border-left: 4px solid var(--color-info);
      transition: all var(--transition-base);
    }

    .detail-card:hover {
      transform: translateY(-3px);
      box-shadow: var(--shadow-md);
    }

    .detail-card.purple { border-left-color: #8B5CF6; }
    .detail-card.green { border-left-color: var(--color-success); }
    .detail-card.orange { border-left-color: var(--color-aws-orange); }
    .detail-card.red { border-left-color: var(--color-error); }

    .detail-card h4 {
      font-size: 1.05em;
      margin-bottom: var(--spacing-sm);
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .detail-card p {
      font-size: 0.92em;
      line-height: var(--line-height-relaxed);
      color: var(--color-text-secondary);
    }

    /* ========================================
       Step Flow
       ======================================== */
    .step-flow {
      display: flex;
      flex-direction: column;
      gap: var(--spacing-md);
      margin-bottom: var(--spacing-base);
    }

    .step-item {
      display: flex;
      align-items: flex-start;
      gap: var(--spacing-md);
      background: var(--color-bg-white);
      padding: var(--spacing-base);
      border-radius: var(--radius-base);
      box-shadow: var(--shadow-xs);
    }

    .step-number {
      width: 40px;
      height: 40px;
      background: var(--color-info);
      color: var(--color-text-white);
      border-radius: var(--radius-full);
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: var(--font-weight-bold);
      font-size: 1em;
      flex-shrink: 0;
    }

    .step-number.purple { background: #8B5CF6; }

    .step-content h4 {
      font-size: 1em;
      margin-bottom: 6px;
    }

    .step-content p {
      font-size: 0.92em;
      color: var(--color-text-secondary);
      line-height: var(--line-height-relaxed);
    }

    /* ========================================
       Tabbed Code Examples
       ======================================== */
    .code-tabs {
      margin-bottom: var(--spacing-base);
    }

    .tab-buttons {
      display: flex;
      gap: 4px;
      border-bottom: 2px solid var(--color-border-light);
      padding-bottom: 0;
    }

    .tab-btn {
      padding: 10px 20px;
      border: none;
      background: var(--color-bg-light);
      color: var(--color-text-secondary);
      font-size: 0.9em;
      font-weight: var(--font-weight-medium);
      cursor: pointer;
      border-radius: var(--radius-sm) var(--radius-sm) 0 0;
      transition: all var(--transition-base);
      font-family: inherit;
    }

    .tab-btn.active {
      background: var(--color-aws-dark);
      color: var(--color-text-white);
    }

    .tab-btn:hover:not(.active) {
      background: var(--color-border-light);
    }

    .tab-content {
      display: none;
      background: #1E293B;
      border-radius: 0 0 var(--radius-base) var(--radius-base);
      padding: var(--spacing-base);
      overflow-x: auto;
    }

    .tab-content.active {
      display: block;
    }

    .tab-content pre {
      margin: 0;
      font-family: 'Courier New', Consolas, monospace;
      font-size: 0.82em;
      line-height: 1.7;
      color: #E2E8F0;
      white-space: pre;
    }

    .tab-content .comment { color: #64748B; }
    .tab-content .keyword { color: #7DD3FC; }
    .tab-content .string { color: #86EFAC; }
    .tab-content .param { color: #FDE68A; }

    /* ========================================
       Best Practice / Anti-pattern
       ======================================== */
    .practice-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: var(--spacing-base);
      margin-bottom: var(--spacing-base);
    }

    .practice-card {
      background: var(--color-bg-white);
      border-radius: var(--radius-lg);
      padding: var(--spacing-xl);
      box-shadow: var(--shadow-sm);
    }

    .practice-card.best {
      border-top: 4px solid var(--color-success);
    }

    .practice-card.anti {
      border-top: 4px solid var(--color-error);
    }

    .practice-card h3 {
      display: flex;
      align-items: center;
      gap: 8px;
      margin-bottom: var(--spacing-md);
    }

    .practice-list {
      list-style: none;
      padding: 0;
    }

    .practice-list li {
      padding: 10px 0;
      border-bottom: 1px solid var(--color-border-light);
      font-size: 0.92em;
      line-height: var(--line-height-relaxed);
      display: flex;
      gap: 10px;
      align-items: flex-start;
    }

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

    /* ========================================
       Troubleshooting
       ======================================== */
    .trouble-item {
      background: var(--color-bg-white);
      border-radius: var(--radius-base);
      padding: var(--spacing-base);
      margin-bottom: var(--spacing-md);
      box-shadow: var(--shadow-xs);
      border-left: 4px solid var(--color-warning);
    }

    .trouble-item h4 {
      color: var(--color-warning);
      font-size: 1em;
      margin-bottom: 8px;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .trouble-cause {
      font-size: 0.92em;
      color: var(--color-text-secondary);
      margin-bottom: 8px;
    }

    .trouble-fix {
      font-size: 0.92em;
      background: #F0FDF4;
      border: 1px solid #BBF7D0;
      border-radius: var(--radius-sm);
      padding: 10px 14px;
    }

    /* ========================================
       Exam Tips
       ======================================== */
    .exam-tip-box {
      background: linear-gradient(135deg, #EEF2FF 0%, #F5F3FF 100%);
      border: 2px solid #818CF8;
      border-radius: var(--radius-lg);
      padding: var(--spacing-xl);
      margin-bottom: var(--spacing-base);
    }

    .exam-tip-box h3 {
      color: #6366F1;
      display: flex;
      align-items: center;
      gap: 8px;
      margin-bottom: var(--spacing-md);
    }

    .exam-tip-list {
      list-style: none;
      padding: 0;
    }

    .exam-tip-list li {
      padding: 10px 0;
      border-bottom: 1px solid rgba(129, 140, 248, 0.2);
      font-size: 0.95em;
      line-height: var(--line-height-relaxed);
      display: flex;
      gap: 10px;
      align-items: flex-start;
    }

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

    /* ========================================
       FAQ Accordion
       ======================================== */
    .faq-item {
      background: var(--color-bg-white);
      border-radius: var(--radius-base);
      margin-bottom: var(--spacing-sm);
      box-shadow: var(--shadow-xs);
      overflow: hidden;
    }

    .faq-question {
      width: 100%;
      text-align: left;
      padding: var(--spacing-base);
      border: none;
      background: none;
      font-size: 0.98em;
      font-weight: var(--font-weight-semibold);
      color: var(--color-text-primary);
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: var(--spacing-sm);
      font-family: inherit;
      transition: background var(--transition-base);
    }

    .faq-question:hover {
      background: var(--color-bg-light);
    }

    .faq-toggle {
      font-size: 1.2em;
      color: var(--color-aws-orange);
      transition: transform var(--transition-base);
      flex-shrink: 0;
    }

    .faq-item.open .faq-toggle {
      transform: rotate(45deg);
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, padding 0.4s ease;
    }

    .faq-item.open .faq-answer {
      max-height: 600px;
      padding: 0 var(--spacing-base) var(--spacing-base);
    }

    .faq-answer p {
      font-size: 0.92em;
      line-height: var(--line-height-relaxed);
      color: var(--color-text-secondary);
    }

    /* ========================================
       Cheat Sheet
       ======================================== */
    .cheat-sheet {
      background: linear-gradient(135deg, #232F3E 0%, #37475A 100%);
      color: var(--color-text-white);
      border-radius: var(--radius-xl);
      padding: var(--spacing-xl);
      margin-bottom: var(--spacing-base);
    }

    .cheat-sheet h2 {
      color: var(--color-aws-orange-original);
      border-bottom-color: rgba(255, 153, 0, 0.3);
    }

    .cheat-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: var(--spacing-base);
    }

    .cheat-item {
      background: rgba(255, 255, 255, 0.08);
      border-radius: var(--radius-base);
      padding: var(--spacing-base);
      border: 1px solid rgba(255, 255, 255, 0.1);
    }

    .cheat-item h4 {
      color: var(--color-aws-orange-original);
      font-size: 0.95em;
      margin-bottom: 8px;
    }

    .cheat-item p {
      font-size: 0.88em;
      color: rgba(255, 255, 255, 0.8);
      line-height: var(--line-height-relaxed);
    }

    /* ========================================
       Highlight box
       ======================================== */
    .highlight-box {
      background: #FFF7ED;
      border: 1px solid #FDBA74;
      border-radius: var(--radius-base);
      padding: var(--spacing-base);
      margin-bottom: var(--spacing-md);
    }

    .highlight-box.info {
      background: #EFF6FF;
      border-color: #93C5FD;
    }

    .highlight-box.warning {
      background: #FEF3C7;
      border-color: #FCD34D;
    }

    .highlight-box.danger {
      background: #FEF2F2;
      border-color: #FCA5A5;
    }

    .highlight-box p {
      font-size: 0.92em;
      line-height: var(--line-height-relaxed);
    }

    /* ========================================
       Inline code
       ======================================== */
    code {
      background: #F1F5F9;
      padding: 2px 8px;
      border-radius: 4px;
      font-family: 'Courier New', Consolas, monospace;
      font-size: 0.88em;
      color: #BE185D;
    }

    /* ========================================
       Scroll to Top Button
       ======================================== */
    .scroll-to-top {
      position: fixed;
      bottom: var(--spacing-xl);
      right: var(--spacing-xl);
      width: 50px;
      height: 50px;
      background: linear-gradient(135deg, var(--color-aws-orange-original) 0%, var(--color-aws-orange-hover) 100%);
      color: var(--color-text-white);
      border: none;
      border-radius: var(--radius-full);
      font-size: var(--font-size-xl);
      cursor: pointer;
      box-shadow: var(--shadow-orange);
      opacity: 0;
      visibility: hidden;
      transition: all var(--transition-base);
      z-index: var(--z-scroll-top);
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .scroll-to-top.show {
      opacity: 1;
      visibility: visible;
    }

    .scroll-to-top:hover {
      transform: translateY(-5px);
      box-shadow: var(--shadow-orange-hover);
    }

    /* ========================================
       SVG Container
       ======================================== */
    .svg-container {
      margin: var(--spacing-base) 0;
      text-align: center;
      overflow-x: auto;
    }

    .svg-container svg {
      max-width: 100%;
      height: auto;
    }

    /* ========================================
       TOC
       ======================================== */
    .toc {
      background: var(--color-bg-white);
      border: 1px solid var(--color-border-light);
      border-radius: var(--radius-lg);
      padding: var(--spacing-xl);
      margin-bottom: var(--spacing-2xl);
    }

    .toc h2 {
      font-size: 1.2em;
      margin-bottom: var(--spacing-md);
      padding-bottom: var(--spacing-sm);
      border-bottom: 2px solid var(--color-aws-orange);
    }

    .toc-list {
      list-style: none;
      padding: 0;
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
      gap: 8px;
    }

    .toc-list li a {
      display: block;
      padding: 10px 14px;
      color: var(--color-text-primary);
      text-decoration: none;
      font-size: 0.92em;
      border-radius: var(--radius-sm);
      transition: all var(--transition-base);
      border-left: 3px solid transparent;
    }

    .toc-list li a:hover {
      background: #FFF7ED;
      border-left-color: var(--color-aws-orange);
      color: var(--color-aws-orange);
    }

    /* ========================================
       Warning callout
       ======================================== */
    .callout {
      display: flex;
      gap: var(--spacing-md);
      align-items: flex-start;
      background: var(--color-bg-white);
      border-radius: var(--radius-base);
      padding: var(--spacing-base);
      margin-bottom: var(--spacing-md);
      border-left: 4px solid var(--color-error);
    }

    .callout.info-callout { border-left-color: var(--color-info); }
    .callout.warn-callout { border-left-color: var(--color-warning); }

    .callout-icon {
      font-size: 1.3em;
      flex-shrink: 0;
    }

    .callout-content p {
      font-size: 0.92em;
      line-height: var(--line-height-relaxed);
    }

    /* ========================================
       Glossary
       ======================================== */
    .glossary-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
      gap: var(--spacing-md);
    }

    .glossary-item {
      background: var(--color-bg-white);
      border-radius: var(--radius-base);
      padding: var(--spacing-base);
      box-shadow: var(--shadow-xs);
    }

    .glossary-item dt {
      font-weight: var(--font-weight-bold);
      color: var(--color-aws-orange);
      margin-bottom: 6px;
      font-size: 0.95em;
    }

    .glossary-item dd {
      font-size: 0.88em;
      color: var(--color-text-secondary);
      line-height: var(--line-height-relaxed);
      margin: 0;
    }

    /* ========================================
       Responsive
       ======================================== */
    @media (max-width: 768px) {
      body { padding: var(--spacing-sm); padding-top: 70px; }
      .container { padding: var(--spacing-base); }
      .compare-grid, .practice-grid, .cheat-grid { grid-template-columns: 1fr; }
      .hero h1 { font-size: 1.6em; }
      .fixed-nav-links { display: none; }
    }

    /* ========================================
       Accessibility: Focus
       ======================================== */
    a:focus, button:focus, [tabindex]:focus {
      outline: 3px solid var(--color-aws-orange-original);
      outline-offset: 2px;
    }