/* ========================================
   CSS Variables & Root Styles
   ======================================== */
:root {
    /* Dark Mode Colors */
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-tertiary: #404040;
    --text-primary: #f8f9fa;
    --text-secondary: #adb5bd;
    --text-muted: #6c757d;
    --border-color: #404040;
    --accent-light: #1a3a52;
    
    /* Accent Colors - Aviation Theme */
    --accent-primary: #2563eb;
    --accent-secondary: #1e40af;
    --accent-hover: #3b82f6;
    
    /* Functional Colors */
    --success: #28a745;
    --warning: #ffc107;
    --danger: #dc3545;
    --info: #17a2b8;
    
    /* UI Elements */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.5);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Typography */
    --font-body: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica', 'Arial', sans-serif;
    --font-mono: 'Courier New', Courier, monospace;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-body);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* ========================================
   Typography
   ======================================== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.3;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; margin-top: var(--spacing-lg); }
h3 { font-size: 1.5rem; margin-top: var(--spacing-md); }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.1rem; }
h6 { font-size: 1rem; }

p {
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.lead {
    font-size: 1.25rem;
    font-weight: 300;
    color: var(--text-secondary);
    line-height: 1.8;
}

a {
    color: var(--accent-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--accent-hover);
}

code {
    font-family: var(--font-mono);
    background: var(--bg-tertiary);
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    font-size: 0.9em;
}

/* ========================================
   Navigation Bar
   ======================================== */
#navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: var(--bg-primary);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    z-index: 1000;
    transition: background-color var(--transition-normal);
    border-bottom: 1px solid var(--border-color);
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-sm) var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
}

.logo-icon {
    font-size: 1.5rem;
}

.progress-bar {
    position: absolute;
    bottom: 0;
    left: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent-primary), var(--info));
    width: 0%;
    transition: width var(--transition-fast);
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
    margin-top: 70px;
    background: #1a5490;
    color: white;
    padding: var(--spacing-xl) var(--spacing-md);
    text-align: center;
    position: relative;
    overflow: hidden;
    border-bottom: 3px solid #0d3a66;
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    color: white;
    font-size: 2.8rem;
    margin-bottom: var(--spacing-sm);
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.5);
    font-weight: 700;
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-lg);
    opacity: 0.95;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-sm);
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: 8px;
    font-weight: 500;
    transition: all var(--transition-fast);
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn-primary {
    background: #ffd700;
    color: #1a1a1a;
    font-weight: 600;
}

.btn-primary:hover {
    background: #ffed4e;
}

.btn-secondary {
    background: transparent;
    color: white;
    border: 2px solid white;
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.15);
}

.scroll-indicator {
    margin-top: var(--spacing-xl);
    animation: bounce 2s infinite;
}

.scroll-indicator span {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-size: 0.9rem;
    opacity: 0.8;
}

.scroll-arrow {
    font-size: 2rem;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(10px); }
}

/* ========================================
   Main Content Container
   ======================================== */
.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-lg) var(--spacing-md);
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: var(--spacing-xl);
}

@media (max-width: 1024px) {
    .container {
        grid-template-columns: 1fr;
    }
}

/* ========================================
   Table of Contents
   ======================================== */
.toc {
    position: sticky;
    top: 90px;
    height: fit-content;
    max-height: calc(100vh - 110px);
    overflow-y: auto;
    background: var(--bg-secondary);
    border-radius: 12px;
    padding: var(--spacing-md);
    box-shadow: var(--shadow-sm);
}

.toc::-webkit-scrollbar {
    width: 6px;
}

.toc::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
    border-radius: 3px;
}

.toc::-webkit-scrollbar-thumb {
    background: var(--accent-primary);
    border-radius: 3px;
}

.toc::-webkit-scrollbar-thumb:hover {
    background: var(--accent-hover);
}

.toc h3 {
    margin-top: 0;
    margin-bottom: var(--spacing-sm);
    color: var(--accent-primary);
    font-size: 1.1rem;
}

#tocList {
    list-style: none;
}

#tocList li {
    margin-bottom: var(--spacing-xs);
}

#tocList a {
    display: block;
    padding: var(--spacing-xs);
    border-radius: 6px;
    color: var(--text-secondary);
    font-size: 0.9rem;
    transition: all var(--transition-fast);
}

#tocList a:hover {
    background: var(--bg-tertiary);
    color: var(--accent-primary);
    padding-left: var(--spacing-sm);
}

@media (max-width: 1024px) {
    .toc {
        display: none;
    }
}

/* ========================================
   Content Sections
   ======================================== */
.content {
    background: var(--bg-primary);
}

.section {
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
}

.section:last-child {
    border-bottom: none;
}

/* ========================================
   Info Boxes & Cards
   ======================================== */
.info-box {
    background: var(--accent-light);
    border-left: 4px solid var(--accent-primary);
    padding: var(--spacing-md);
    border-radius: 8px;
    margin: var(--spacing-md) 0;
}

.info-box.highlight {
    background: #fff7ed;
    border-left: 4px solid #f59e0b;
}

[data-theme="dark"] .info-box.highlight {
    background: #451a03;
    border-left-color: #f59e0b;
}

.warning-box {
    background: rgba(255, 193, 7, 0.1);
    border-left: 4px solid var(--warning);
    padding: var(--spacing-md);
    border-radius: 8px;
    margin: var(--spacing-md) 0;
}

.tip-box {
    background: rgba(40, 167, 69, 0.1);
    border-left: 4px solid var(--success);
    padding: var(--spacing-md);
    border-radius: 8px;
    margin: var(--spacing-md) 0;
}

/* ========================================
   Priority Cards
   ======================================== */
.priority-card {
    background: var(--bg-secondary);
    border-radius: 12px;
    padding: var(--spacing-md);
    margin: var(--spacing-md) 0;
    box-shadow: var(--shadow-sm);
}

.priority-badge {
    background: var(--accent-primary);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
    margin-right: var(--spacing-xs);
}

.priority-card h3 {
    margin-top: 0;
    margin-bottom: var(--spacing-md);
}

.priority-card dl {
    margin: 0;
}

.priority-card dt {
    font-weight: 600;
    color: var(--accent-primary);
    margin-top: var(--spacing-sm);
    margin-bottom: var(--spacing-xs);
}

.priority-card dd {
    margin-left: 0;
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
}

/* ========================================
   Movement & Instrument Cards
   ======================================== */
.movement-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin: var(--spacing-md) 0;
}

.movement-card {
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 12px;
    text-align: center;
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition-fast);
}

.movement-card:hover {
    background: var(--bg-tertiary);
}

.movement-icon {
    font-size: 3rem;
    margin: var(--spacing-sm) 0;
}

.instruments-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-md);
    margin: var(--spacing-md) 0;
}

.instrument-card {
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    position: relative;
    transition: all var(--transition-fast);
}

.instrument-card:hover {
    border: 1px solid var(--accent-primary);
}

.instrument-number {
    position: absolute;
    top: 10px;
    right: 10px;
    width: 30px;
    height: 30px;
    background: var(--accent-primary);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 0.9rem;
}

.instrument-card h4 {
    margin-top: 0;
    color: var(--accent-primary);
}

/* ========================================
   Accordion
   ======================================== */
.accordion {
    margin: var(--spacing-md) 0;
}

.accordion-item {
    background: var(--bg-secondary);
    border-radius: 8px;
    margin-bottom: var(--spacing-xs);
    overflow: hidden;
}

.accordion-header {
    padding: var(--spacing-sm) var(--spacing-md);
    cursor: pointer;
    background: var(--bg-tertiary);
    margin: 0;
    transition: background var(--transition-fast);
    position: relative;
    padding-right: 3rem;
}

.accordion-header:hover {
    background: var(--border-color);
}

.accordion-header::after {
    content: '▼';
    position: absolute;
    right: var(--spacing-md);
    top: 50%;
    transform: translateY(-50%);
    transition: transform var(--transition-fast);
}

.accordion-item.active .accordion-header::after {
    transform: translateY(-50%) rotate(180deg);
}

.accordion-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-normal);
    padding: 0 var(--spacing-md);
}

.accordion-item.active .accordion-content {
    max-height: 500px;
    padding: var(--spacing-md);
}

/* ========================================
   Procedures & Lists
   ======================================== */
.procedure-list {
    background: var(--bg-secondary);
    padding: var(--spacing-md) var(--spacing-md) var(--spacing-md) var(--spacing-xl);
    border-radius: 8px;
    margin: var(--spacing-md) 0;
}

.procedure-list li {
    margin-bottom: var(--spacing-sm);
    padding-left: var(--spacing-xs);
}

.procedure-list li strong {
    color: var(--accent-primary);
}

/* ========================================
   Career & Practice Cards
   ======================================== */
.career-grid,
.practice-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-md);
    margin: var(--spacing-md) 0;
}

.career-card,
.practice-card {
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-fast);
    border-top: 4px solid var(--accent-primary);
}

.career-card:hover,
.practice-card:hover {
    border-top: 4px solid var(--accent-hover);
}

.career-card h4,
.practice-card h4 {
    color: var(--accent-primary);
    margin-top: 0;
}

/* ========================================
   Aerodynamics Grid
   ======================================== */
.aero-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin: var(--spacing-md) 0;
}

.aero-card {
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-tertiary) 100%);
    padding: var(--spacing-md);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
}

.aero-card h4 {
    color: var(--accent-primary);
    margin-top: 0;
}

/* ========================================
   Mistakes Grid
   ======================================== */
.mistakes-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-md);
    margin: var(--spacing-md) 0;
}

.mistake-card {
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 12px;
    border-left: 4px solid var(--danger);
    box-shadow: var(--shadow-sm);
}

.mistake-card h4 {
    color: var(--danger);
    margin-top: 0;
}

.mistake-card p {
    margin-bottom: var(--spacing-xs);
    font-size: 0.95rem;
}

/* ========================================
   Radio Communication
   ======================================== */
.radio-example {
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 8px;
    margin: var(--spacing-sm) 0;
    border-left: 4px solid var(--info);
}

.radio-example .example {
    font-family: var(--font-mono);
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-top: var(--spacing-xs);
}

.phonetic-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: var(--spacing-xs);
    margin: var(--spacing-md) 0;
}

.phonetic-grid span {
    background: var(--bg-secondary);
    padding: var(--spacing-xs);
    border-radius: 6px;
    text-align: center;
    font-size: 0.9rem;
}

/* ========================================
   Timeline (Assistance Settings)
   ======================================== */
.progression-timeline {
    margin: var(--spacing-lg) 0;
}

.timeline-item {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.timeline-badge {
    background: var(--accent-primary);
    color: white;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 20px;
    font-weight: 600;
    height: fit-content;
    white-space: nowrap;
}

.timeline-content {
    flex: 1;
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
}

.timeline-content h4 {
    margin-top: 0;
    color: var(--accent-primary);
}

/* ========================================
   Add-ons Grid
   ======================================== */
.addons-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin: var(--spacing-md) 0;
}

.addon-card {
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    position: relative;
    transition: all var(--transition-fast);
}

.addon-card:hover {
    background: var(--bg-tertiary);
}

.addon-card h4 {
    color: var(--accent-primary);
    margin-top: 0;
}

.addon-tag {
    position: absolute;
    top: 10px;
    right: 10px;
    background: var(--accent-primary);
    color: white;
    padding: 0.25rem 0.5rem;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
}

.addon-tag.recommended {
    background: var(--info);
}

/* ========================================
   Shortcuts Grid
   ======================================== */
.shortcuts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-md);
    margin: var(--spacing-md) 0;
}

.shortcut-card {
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 12px;
    text-align: center;
    box-shadow: var(--shadow-sm);
}

.shortcut-key {
    background: var(--accent-primary);
    color: white;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 8px;
    font-family: var(--font-mono);
    font-weight: 600;
    display: inline-block;
    margin-bottom: var(--spacing-xs);
}

.shortcut-desc {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* ========================================
   Controller Table
   ======================================== */
.controller-table {
    width: 100%;
    border-collapse: collapse;
    margin: var(--spacing-md) 0;
    background: var(--bg-secondary);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.controller-table thead {
    background: var(--accent-primary);
    color: white;
}

.controller-table th,
.controller-table td {
    padding: var(--spacing-sm);
    text-align: left;
}

.controller-table tbody tr {
    border-bottom: 1px solid var(--border-color);
}

.controller-table tbody tr:last-child {
    border-bottom: none;
}

.controller-table tbody tr:hover {
    background: var(--bg-tertiary);
}

/* ========================================
   Checklist
   ======================================== */
.checklist {
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 12px;
    margin: var(--spacing-md) 0;
}

.checklist-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm);
    margin-bottom: var(--spacing-xs);
    border-radius: 8px;
    cursor: pointer;
    transition: background var(--transition-fast);
}

.checklist-item:hover {
    background: var(--bg-tertiary);
}

.checklist-item input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

.checklist-item span {
    flex: 1;
}

/* ========================================
   Footer
   ======================================== */
.footer {
    background: var(--bg-secondary);
    padding: var(--spacing-lg);
    text-align: center;
    margin-top: var(--spacing-xl);
    border-top: 1px solid var(--border-color);
}

.footer-content p {
    margin-bottom: var(--spacing-xs);
    color: var(--text-secondary);
}

/* ========================================
   Utility Classes
   ======================================== */
ul, ol {
    margin-left: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
}

li {
    margin-bottom: var(--spacing-xs);
}

strong {
    font-weight: 600;
    color: var(--text-primary);
}

/* ========================================
   Responsive Design
   ======================================== */
@media (max-width: 768px) {
    html {
        font-size: 14px;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1.2rem;
    }

    .container {
        padding: var(--spacing-md) var(--spacing-sm);
    }

    .movement-grid,
    .instruments-grid,
    .career-grid,
    .practice-grid,
    .addons-grid,
    .shortcuts-grid {
        grid-template-columns: 1fr;
    }

    .phonetic-grid {
        grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    }
}

/* ========================================
   Print Styles
   ======================================== */
@media print {
    .hero,
    #navbar,
    .toc,
    .footer {
        display: none;
    }

    .container {
        grid-template-columns: 1fr;
    }

    .section {
        page-break-inside: avoid;
    }
}

/* ========================================
   Animations
   ======================================== */
/* Smooth scrolling offset for fixed header */
html {
    scroll-padding-top: 90px;
}