/* ==========================================
   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);
  --z-base: 1;
  --z-sticky: 500;
  --z-scroll-top: 1000;
  --z-progress-bar: 1001;
  --z-header: 1002;
  --transition-fast: 0.15s ease;
  --transition-base: 0.3s ease;
  --transition-slow: 0.5s ease;
  --header-height: 60px;
  --container-max-width: 1200px;
}

/* ==========================================
   Hero Section
   ========================================== */
.hero {
  background: linear-gradient(135deg, #232F3E 0%, #37475A 100%);
  border-radius: var(--radius-xl);
  padding: var(--spacing-3xl) var(--spacing-2xl);
  margin-bottom: var(--spacing-2xl);
  color: var(--color-text-white);
  text-align: center;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -30%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(255,153,0,0.15) 0%, transparent 70%);
  border-radius: 50%;
}
.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: 2em;
  font-weight: var(--font-weight-bold);
  margin-bottom: var(--spacing-sm);
  color: var(--color-text-white);
}
.hero-subtitle {
  font-size: 1.1em;
  color: #D1D5DB;
  margin-bottom: var(--spacing-xl);
}

/* ==========================================
   Key Takeaways
   ========================================== */
.takeaways {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--spacing-base);
  margin-bottom: var(--spacing-2xl);
}
.takeaway-card {
  background: var(--color-bg-light);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  border-left: 5px solid var(--color-aws-orange);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-base);
}
.takeaway-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}
.takeaway-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: var(--color-aws-orange);
  color: var(--color-text-white);
  border-radius: var(--radius-full);
  font-weight: var(--font-weight-bold);
  font-size: 0.9em;
  margin-bottom: var(--spacing-sm);
}
.takeaway-card h3 {
  font-size: 1.05em;
  margin-bottom: var(--spacing-xs);
  color: var(--color-text-primary);
}
.takeaway-card p {
  font-size: 0.9em;
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

/* ==========================================
   Section Styles
   ========================================== */
.section {
  margin-bottom: var(--spacing-2xl);
}
.section-header {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
  padding-bottom: var(--spacing-sm);
  border-bottom: 3px solid var(--color-aws-orange);
}
.section-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  background: linear-gradient(135deg, var(--color-aws-orange) 0%, var(--color-aws-orange-hover) 100%);
  color: var(--color-text-white);
  border-radius: var(--radius-base);
  font-size: 1.3em;
  flex-shrink: 0;
}
.section-header h2 {
  font-size: 1.5em;
  color: var(--color-text-primary);
  border-bottom: none;
  padding-bottom: 0;
  margin-bottom: 0;
}

/* ==========================================
   Analogy Box
   ========================================== */
.analogy-intro {
  background: linear-gradient(135deg, #FFF7ED 0%, #FFFBEB 100%);
  border: 2px solid #FDBA74;
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  margin-bottom: var(--spacing-xl);
}
.analogy-intro h3 {
  font-size: 1.2em;
  color: #92400E;
  margin-bottom: var(--spacing-sm);
}
.analogy-intro p {
  font-size: 0.95em;
  color: #78350F;
  line-height: var(--line-height-relaxed);
}

/* ==========================================
   Mapping Table
   ========================================== */
.mapping-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  border-radius: var(--radius-base);
  overflow: hidden;
  margin-bottom: var(--spacing-xl);
  box-shadow: var(--shadow-sm);
}
.mapping-table thead th {
  background: var(--color-aws-dark);
  color: var(--color-text-white);
  padding: var(--spacing-md) var(--spacing-base);
  font-weight: var(--font-weight-semibold);
  font-size: 0.95em;
  text-align: left;
}
.mapping-table tbody td {
  padding: var(--spacing-md) var(--spacing-base);
  border-bottom: 1px solid var(--color-border-light);
  font-size: 0.9em;
  vertical-align: top;
}
.mapping-table tbody tr:nth-child(even) { background: var(--color-bg-light); }
.mapping-table tbody tr:hover { background: #FFF7ED; }
.mapping-table .emoji-col { text-align: center; font-size: 1.3em; width: 50px; }

/* ==========================================
   SVG Diagram Wrapper
   ========================================== */
.svg-wrapper {
  background: var(--color-bg-light);
  border-radius: var(--radius-lg);
  padding: var(--spacing-base);
  margin-bottom: var(--spacing-xl);
  box-shadow: var(--shadow-sm);
  overflow-x: auto;
}
.svg-wrapper svg {
  display: block;
  margin: 0 auto;
  max-width: 100%;
  height: auto;
}

/* ==========================================
   Feature Cards
   ========================================== */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--spacing-base);
  margin-bottom: var(--spacing-xl);
}
.feature-card {
  background: var(--color-bg-white);
  border: 2px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  transition: all var(--transition-base);
}
.feature-card:hover {
  border-color: var(--color-aws-orange);
  box-shadow: var(--shadow-md);
}
.feature-card-header {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
}
.feature-card-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2em;
  flex-shrink: 0;
}
.feature-card h4 {
  font-size: 1em;
  color: var(--color-text-primary);
  margin-bottom: 0;
}
.feature-card p {
  font-size: 0.9em;
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
}

/* ==========================================
   CIDR Binary Section
   ========================================== */
.binary-box {
  background: #F0FDF4;
  border: 2px solid #86EFAC;
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  margin-bottom: var(--spacing-xl);
  font-family: 'Courier New', Courier, monospace;
}
.binary-box h4 {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  color: #166534;
  margin-bottom: var(--spacing-md);
  font-size: 1.05em;
}
.binary-line {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-sm);
  flex-wrap: wrap;
}
.binary-label {
  min-width: 180px;
  font-weight: var(--font-weight-bold);
  color: #166534;
  font-size: 0.85em;
}
.binary-bits {
  font-size: 0.85em;
  color: var(--color-text-primary);
  letter-spacing: 0.5px;
}
.binary-bits .match { color: #16A34A; font-weight: var(--font-weight-bold); }
.binary-bits .diff { color: var(--color-error); font-weight: var(--font-weight-bold); }
.binary-result {
  background: #DCFCE7;
  border-radius: var(--radius-md);
  padding: var(--spacing-md);
  margin-top: var(--spacing-md);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  font-weight: var(--font-weight-semibold);
  color: #166534;
  font-size: 0.95em;
  text-align: center;
}

/* ==========================================
   Best Practices / Anti-patterns
   ========================================== */
.practices-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--spacing-base);
  margin-bottom: var(--spacing-xl);
}
.practice-card {
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
}
.practice-good {
  background: #F0FDF4;
  border: 2px solid #86EFAC;
}
.practice-bad {
  background: #FEF2F2;
  border: 2px solid #FCA5A5;
}
.practice-card h4 {
  font-size: 1.05em;
  margin-bottom: var(--spacing-md);
}
.practice-good h4 { color: #166534; }
.practice-bad h4 { color: #991B1B; }
.practice-item {
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-sm);
  font-size: 0.9em;
  line-height: var(--line-height-relaxed);
}
.practice-item .icon { font-size: 1.1em; flex-shrink: 0; margin-top: 2px; }

/* ==========================================
   Exam Tips
   ========================================== */
.exam-tips {
  background: linear-gradient(135deg, #EEF2FF 0%, #E0E7FF 100%);
  border: 2px solid #818CF8;
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  margin-bottom: var(--spacing-xl);
}
.exam-tips h3 {
  color: #3730A3;
  font-size: 1.15em;
  margin-bottom: var(--spacing-md);
}
.exam-tip-item {
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
  font-size: 0.9em;
  line-height: var(--line-height-relaxed);
  color: #312E81;
}
.exam-tip-item .tip-icon { font-size: 1.2em; flex-shrink: 0; }

/* ==========================================
   Tabbed Code Examples
   ========================================== */
.code-tabs {
  margin-bottom: var(--spacing-xl);
  background: var(--color-bg-light);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}
.tab-buttons {
  display: flex;
  border-bottom: 2px solid var(--color-border-light);
}
.tab-btn {
  padding: var(--spacing-md) var(--spacing-lg);
  background: transparent;
  border: none;
  font-size: 0.9em;
  font-weight: var(--font-weight-semibold);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--transition-base);
  border-bottom: 3px solid transparent;
  margin-bottom: -2px;
}
.tab-btn.active {
  color: var(--color-aws-orange);
  border-bottom-color: var(--color-aws-orange);
  background: var(--color-bg-white);
}
.tab-btn:hover { color: var(--color-aws-orange); }
.tab-panel {
  display: none;
  padding: var(--spacing-base);
}
.tab-panel.active { display: block; }
.tab-panel pre {
  background: #1E293B;
  color: #E2E8F0;
  padding: var(--spacing-base);
  border-radius: var(--radius-md);
  overflow-x: auto;
  font-size: 0.8em;
  line-height: 1.6;
  font-family: 'Courier New', Courier, monospace;
}

/* ==========================================
   FAQ Accordion
   ========================================== */
.faq-list { margin-bottom: var(--spacing-xl); }
.faq-item {
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-base);
  margin-bottom: var(--spacing-sm);
  overflow: hidden;
  box-shadow: var(--shadow-xs);
}
.faq-question {
  width: 100%;
  padding: var(--spacing-base) var(--spacing-lg);
  background: var(--color-bg-white);
  border: none;
  text-align: left;
  font-size: 0.95em;
  font-weight: var(--font-weight-semibold);
  color: var(--color-text-primary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-md);
  transition: background var(--transition-base);
}
.faq-question:hover { background: var(--color-bg-light); }
.faq-question .arrow {
  font-size: 1.2em;
  transition: transform var(--transition-base);
  flex-shrink: 0;
}
.faq-item.open .faq-question .arrow { transform: rotate(180deg); }
.faq-answer {
  display: none;
  padding: 0 var(--spacing-lg) var(--spacing-base);
  font-size: 0.9em;
  color: var(--color-text-secondary);
  line-height: var(--line-height-relaxed);
  background: var(--color-bg-light);
  border-top: 1px solid var(--color-border-light);
}
.faq-item.open .faq-answer { display: block; padding-top: var(--spacing-base); }

/* ==========================================
   Cheat Sheet
   ========================================== */
.cheatsheet {
  background: linear-gradient(135deg, #FEFCE8 0%, #FEF9C3 100%);
  border: 2px solid #FACC15;
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  margin-bottom: var(--spacing-xl);
}
.cheatsheet h3 {
  color: #854D0E;
  font-size: 1.15em;
  margin-bottom: var(--spacing-md);
}
.cheatsheet-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--spacing-md);
}
.cheatsheet-item {
  background: rgba(255,255,255,0.7);
  border-radius: var(--radius-md);
  padding: var(--spacing-md);
}
.cheatsheet-item dt {
  font-weight: var(--font-weight-bold);
  color: #854D0E;
  font-size: 0.9em;
  margin-bottom: 4px;
}
.cheatsheet-item dd {
  font-size: 0.85em;
  color: #713F12;
  line-height: var(--line-height-normal);
}

/* ==========================================
   Troubleshooting
   ========================================== */
.trouble-card {
  background: var(--color-bg-white);
  border: 2px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-md);
}
.trouble-card h4 {
  color: var(--color-error);
  font-size: 1em;
  margin-bottom: var(--spacing-sm);
}
.trouble-cause {
  font-size: 0.9em;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-sm);
}
.trouble-fix {
  background: #F0FDF4;
  border-radius: var(--radius-md);
  padding: var(--spacing-md);
  font-size: 0.9em;
  color: #166534;
}

/* ==========================================
   Callout Box
   ========================================== */
.callout {
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-xl);
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-md);
}
.callout-icon { font-size: 1.5em; flex-shrink: 0; }
.callout-warning {
  background: #FFFBEB;
  border: 2px solid #FCD34D;
}
.callout-info {
  background: #EFF6FF;
  border: 2px solid #93C5FD;
}
.callout h4 {
  font-size: 1em;
  margin-bottom: var(--spacing-xs);
}
.callout p {
  font-size: 0.9em;
  line-height: var(--line-height-relaxed);
}

/* ==========================================
   TOC
   ========================================== */
.toc {
  background: var(--color-bg-light);
  border-radius: var(--radius-lg);
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-2xl);
  box-shadow: var(--shadow-sm);
}
.toc h3 {
  font-size: 1.1em;
  margin-bottom: var(--spacing-md);
  color: var(--color-text-primary);
}
.toc-list {
  list-style: none;
  padding: 0;
}
.toc-list li {
  margin-bottom: var(--spacing-xs);
}
.toc-list a {
  color: var(--color-info);
  text-decoration: none;
  font-size: 0.9em;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: 6px var(--spacing-sm);
  border-radius: var(--radius-sm);
  transition: all var(--transition-base);
}
.toc-list a:hover {
  background: rgba(59,130,246,0.1);
  color: #1D4ED8;
}
.toc-num {
  color: var(--color-aws-orange);
  font-weight: var(--font-weight-bold);
  min-width: 30px;
}

/* ==========================================
   Glossary
   ========================================== */
.glossary-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-xl);
}
.glossary-item {
  background: var(--color-bg-light);
  border-radius: var(--radius-md);
  padding: var(--spacing-md);
  border-left: 4px solid var(--color-info);
}
.glossary-item dt {
  font-weight: var(--font-weight-bold);
  color: var(--color-text-primary);
  font-size: 0.95em;
  margin-bottom: 4px;
}
.glossary-item dd {
  font-size: 0.85em;
  color: var(--color-text-secondary);
  line-height: var(--line-height-normal);
}

/* ==========================================
   Responsive
   ========================================== */
@media (max-width: 768px) {
  .hero { padding: var(--spacing-2xl) var(--spacing-base); }
  .hero h1 { font-size: 1.5em; }
  .takeaways, .feature-grid, .practices-grid, .cheatsheet-grid { grid-template-columns: 1fr; }
  .binary-label { min-width: 140px; }
}