/* =====================================================
   World Regional Geography - Design System
   ===================================================== */

/* CSS Custom Properties (Design Tokens) */
:root {
    /* Colors - RSGEE Inspired Palette */
    --color-primary: #4A90A4;
    --color-primary-dark: #3a7282;
    --color-primary-light: #6db0c2;
    --color-secondary: #f4a261; /* Keeping secondary as accent */
    --color-secondary-dark: #e07b3c;
    
    /* Neutrals */
    --color-bg: #F5F5F5;
    --color-bg-alt: #ffffff; /* White cards on light gray bg */
    --color-surface: #ffffff;
    --color-text: #333333;
    --color-text-light: #555555;
    --color-text-muted: #777777;
    --color-border: #e0e0e0;
    
    /* Semantic Colors - Soft Callout Tones */
    --color-success-bg: #e6f4ea;
    --color-success-border: #137333;
    --color-info-bg: #e8f0fe;
    --color-info-border: #1967d2;
    --color-warning-bg: #fef7e0;
    --color-warning-border: #ea8600;
    
    /* Typography */
    --font-stack: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-heading: var(--font-stack);
    --font-body: var(--font-stack);
    
    /* Font Sizes (fluid scale) */
    --text-xs: 0.875rem;
    --text-sm: 1rem;
    --text-base: 1.125rem;
    --text-lg: 1.25rem;
    --text-xl: 1.5rem;
    --text-2xl: 1.75rem;
    --text-3xl: 2rem;
    --text-4xl: 2.5rem;
    
    /* Spacing */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    --space-16: 4rem;
    --space-20: 5rem;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 6px;
    --radius-lg: 8px;
    --radius-xl: 12px;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(60,64,67,0.3), 0 1px 3px 1px rgba(60,64,67,0.15);
    --shadow-md: 0 1px 3px 0 rgba(60,64,67,0.3), 0 4px 8px 3px rgba(60,64,67,0.15);
    --shadow-lg: 0 2px 6px 2px rgba(60,64,67,0.15), 0 1px 2px 0 rgba(60,64,67,0.3);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    
    /* Layout */
    --container-max: 1200px;
    --header-height: 64px;
}

/* Dark Mode - Simplified */
@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #202124;
        --color-bg-alt: #292a2d;
        --color-surface: #2d2e30;
        --color-text: #e8eaed;
        --color-text-light: #9aa0a6;
        --color-border: #3c4043;
    }
}

/* =====================================================
   Reset & Base Styles
   ===================================================== */

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

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-body);
    font-size: var(--text-base);
    line-height: 1.7;
    color: var(--color-text);
    background-color: var(--color-bg);
    min-height: 100vh;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: 1.3;
    color: var(--color-text);
}

h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-2xl); }
h4 { font-size: var(--text-xl); }

p {
    margin-bottom: var(--space-4);
}

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

a:hover {
    color: var(--color-primary-light);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

button {
    cursor: pointer;
    font-family: inherit;
}

ul, ol {
    list-style-position: inside;
}

/* =====================================================
   Utility Classes
   ===================================================== */

.container {
    width: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--space-6);
}

.section-title {
    text-align: center;
    margin-bottom: var(--space-4);
    color: var(--color-text);
}

.section-subtitle {
    text-align: center;
    color: var(--color-text-muted);
    margin-bottom: var(--space-12);
    font-size: var(--text-lg);
}

/* =====================================================
   Buttons
   ===================================================== */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--space-3) var(--space-6);
    font-size: var(--text-base);
    font-weight: 600;
    border-radius: var(--radius-md);
    border: 2px solid transparent;
    transition: all var(--transition-base);
    text-decoration: none;
    cursor: pointer;
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: white;
    border-color: var(--color-primary);
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--color-primary-light) 0%, var(--color-primary) 100%);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

.btn-secondary:hover {
    background: white;
    color: var(--color-primary);
}

/* =====================================================
   Header & Navigation
   ===================================================== */

.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: var(--color-surface);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
}

.site-header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.header-brand .logo {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    font-family: var(--font-heading);
    font-size: var(--text-lg);
    font-weight: 700;
    color: var(--color-text);
}

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

.main-nav .nav-menu {
    display: flex;
    align-items: center;
    gap: var(--space-6);
    list-style: none;
}

.nav-link {
    font-weight: 600;
    color: var(--color-text-light);
    padding: var(--space-2) var(--space-3);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-primary);
    background: var(--color-bg-alt);
}

/* Dropdown */
.nav-dropdown {
    position: relative;
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 220px;
    background: var(--color-surface);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-xl);
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: all var(--transition-fast);
    list-style: none;
    padding: var(--space-2) 0;
    z-index: 100;
}

.nav-dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-menu li a {
    display: block;
    padding: var(--space-2) var(--space-4);
    color: var(--color-text-light);
    font-size: var(--text-sm);
    transition: all var(--transition-fast);
}

.dropdown-menu li a:hover {
    background: var(--color-bg-alt);
    color: var(--color-primary);
}

/* Mobile Nav Toggle */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    padding: var(--space-2);
}

.hamburger {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--color-text);
    position: relative;
}

.hamburger::before,
.hamburger::after {
    content: '';
    position: absolute;
    width: 100%;
    height: 100%;
    background: var(--color-text);
    left: 0;
}

.hamburger::before { top: -8px; }
.hamburger::after { top: 8px; }

/* Mobile Navigation */
@media (max-width: 768px) {
    .nav-toggle {
        display: block;
    }
    
    .nav-menu {
        position: fixed;
        top: var(--header-height);
        left: 0;
        right: 0;
        background: var(--color-surface);
        flex-direction: column;
        padding: var(--space-6);
        gap: var(--space-4) !important;
        box-shadow: var(--shadow-lg);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-base);
    }
    
    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }
    
    .dropdown-menu {
        position: static;
        opacity: 1;
        visibility: visible;
        transform: none;
        box-shadow: none;
        padding-left: var(--space-4);
        display: none;
    }
    
    .nav-dropdown.active .dropdown-menu {
        display: block;
    }
}

/* =====================================================
   Hero Section
   ===================================================== */

.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    padding-top: var(--header-height);
}

.hero-background {
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, var(--color-primary-dark) 0%, var(--color-primary) 50%, var(--color-accent) 100%);
    z-index: -2;
}

.hero-overlay {
    position: absolute;
    inset: 0;
    background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    z-index: -1;
}

.hero-content {
    text-align: center;
    color: white;
    max-width: 800px;
}

.hero-title {
    font-size: var(--text-4xl);
    margin-bottom: var(--space-6);
    color: white;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
}

.hero-subtitle {
    font-size: var(--text-xl);
    margin-bottom: var(--space-8);
    opacity: 0.95;
    line-height: 1.6;
}

.hero-actions {
    display: flex;
    gap: var(--space-4);
    justify-content: center;
    flex-wrap: wrap;
}

/* =====================================================
   About Section
   ===================================================== */

.about-section {
    padding: var(--space-20) 0;
    background: var(--color-surface);
}

.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-12);
    align-items: center;
}

@media (max-width: 768px) {
    .about-grid {
        grid-template-columns: 1fr;
    }
}

.about-content h2 {
    margin-bottom: var(--space-6);
}

.feature-list {
    list-style: none;
    margin-top: var(--space-6);
}

.feature-list li {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-2) 0;
    font-size: var(--text-lg);
}

.feature-icon {
    font-size: 1.5em;
}

.map-preview {
    height: 400px;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    background: var(--color-bg-alt);
}

/* =====================================================
   Regions Grid
   ===================================================== */

.regions-section {
    padding: var(--space-20) 0;
    background: var(--color-bg-alt);
}

.regions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-6);
}

.region-card {
    background: var(--color-surface);
    border-radius: var(--radius-lg);
    padding: var(--space-6);
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
    text-decoration: none;
    border: 2px solid transparent;
}

.region-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
    border-color: var(--color-primary);
}

.region-icon {
    font-size: 3rem;
    margin-bottom: var(--space-4);
}

.region-card h3 {
    font-size: var(--text-lg);
    margin-bottom: var(--space-2);
    color: var(--color-text);
}

.region-card p {
    color: var(--color-text-muted);
    font-size: var(--text-sm);
    margin-bottom: 0;
}

/* =====================================================
   Features Section
   ===================================================== */

.features-section {
    padding: var(--space-20) 0;
    background: var(--color-surface);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-6);
}

.feature-card {
    text-align: center;
    padding: var(--space-8);
    border-radius: var(--radius-lg);
    background: var(--color-bg-alt);
    transition: all var(--transition-base);
}

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

.feature-card-icon {
    font-size: 3rem;
    margin-bottom: var(--space-4);
}

.feature-card h3 {
    font-size: var(--text-lg);
    margin-bottom: var(--space-3);
}

.feature-card p {
    color: var(--color-text-muted);
    margin-bottom: 0;
}

/* =====================================================
   Footer
   ===================================================== */

.site-footer {
    background: var(--color-primary-dark);
    color: white;
    padding: var(--space-12) 0;
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-6);
    text-align: center;
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    font-family: var(--font-heading);
    font-size: var(--text-lg);
    font-weight: 700;
}

.footer-links {
    display: flex;
    gap: var(--space-6);
}

.footer-links a {
    color: rgba(255, 255, 255, 0.8);
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: white;
}

.footer-copyright {
    color: rgba(255, 255, 255, 0.6);
    font-size: var(--text-sm);
}

/* =====================================================
   Chapter Page Styles
   ===================================================== */

.chapter-header {
    background: linear-gradient(135deg, var(--color-primary-dark) 0%, var(--color-primary) 100%);
    color: white;
    padding: calc(var(--header-height) + var(--space-12)) 0 var(--space-12);
}

.chapter-meta {
    font-size: var(--text-sm);
    opacity: 0.8;
    margin-bottom: var(--space-3);
}

.chapter-title {
    color: white;
    margin-bottom: var(--space-4);
}

.chapter-description {
    font-size: var(--text-lg);
    opacity: 0.95;
    max-width: 700px;
}

.chapter-content {
    padding: var(--space-16) 0;
}

.chapter-content .container {
    max-width: 800px;
}

/* Learning Objectives */
.learning-objectives {
    background-color: var(--color-success-bg);
    border-left: 6px solid var(--color-success-border);
    color: var(--color-text);
    border-radius: 4px;
    padding: var(--space-6);
    margin-bottom: var(--space-10);
}

.learning-objectives h2 {
    color: var(--color-success-border);
    font-size: var(--text-xl);
    margin-bottom: var(--space-4);
    display: flex;
    align-items: center;
    gap: var(--space-3);
}

.learning-objectives ul {
    list-style: none;
}

.learning-objectives li {
    padding: var(--space-2) 0;
    padding-left: var(--space-6);
    position: relative;
    color: var(--color-text);
}

.learning-objectives li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--color-success-border);
    font-weight: bold;
}

/* Key Terms */
.key-terms {
    background-color: var(--color-warning-bg);
    border-left: 6px solid var(--color-warning-border);
    border-radius: 4px;
    padding: var(--space-6);
    margin: var(--space-8) 0;
}

.key-terms h3 {
    font-size: var(--text-lg);
    margin-bottom: var(--space-4);
    color: var(--color-warning-border);
}

.term-grid {
    display: grid;
    gap: var(--space-4);
}

.term {
    display: grid;
    grid-template-columns: 150px 1fr;
    gap: var(--space-4);
}

.term dt {
    font-weight: 700;
    color: var(--color-text);
}

.term dd {
    color: var(--color-text-light);
}

/* Case Study */
.case-study {
    background-color: var(--color-info-bg);
    border-left: 6px solid var(--color-info-border);
    border-radius: 4px;
    padding: var(--space-6);
    margin: var(--space-8) 0;
    box-shadow: none; /* Flat style */
}

.case-study-header {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    margin-bottom: var(--space-4);
}

.case-study-label {
    background: var(--color-info-border);
    color: white;
    padding: var(--space-1) var(--space-3);
    border-radius: var(--radius-sm);
    font-size: var(--text-xs);
    font-weight: 700;
    text-transform: uppercase;
}

/* Think Like a Geographer (mapped to Info style for now, or use secondary) */
.think-box {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-left: 6px solid var(--color-primary);
    border-radius: 4px;
    padding: var(--space-6);
    margin: var(--space-8) 0;
    color: var(--color-text);
}

.think-box h3 {
    color: var(--color-primary);
    display: flex;
    align-items: center;
    gap: var(--space-3);
    margin-bottom: var(--space-4);
}

/* Quiz Component */
.quiz-container {
    background: var(--color-bg-alt);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-6);
    margin: var(--space-8) 0;
}

.quiz-question {
    font-weight: 600;
    margin-bottom: var(--space-4);
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.quiz-option {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-3) var(--space-4);
    background: var(--color-surface);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    border: 2px solid transparent;
}

.quiz-option:hover {
    border-color: var(--color-primary);
}

.quiz-option.correct {
    background: rgba(16, 185, 129, 0.1);
    border-color: var(--color-success);
}

.quiz-option.incorrect {
    background: rgba(239, 68, 68, 0.1);
    border-color: var(--color-error);
}

.quiz-feedback {
    margin-top: var(--space-4);
    padding: var(--space-4);
    border-radius: var(--radius-md);
    display: none;
}

.quiz-feedback.show {
    display: block;
}

.quiz-feedback.success {
    background: rgba(16, 185, 129, 0.1);
    color: var(--color-success);
}

.quiz-feedback.error {
    background: rgba(239, 68, 68, 0.1);
    color: var(--color-error);
}

/* Chapter Navigation */
.chapter-nav {
    display: flex;
    justify-content: space-between;
    padding: var(--space-8) 0;
    border-top: 1px solid var(--color-border);
    margin-top: var(--space-12);
}

.chapter-nav-link {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-4) var(--space-6);
    background: var(--color-bg-alt);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.chapter-nav-link:hover {
    background: var(--color-primary);
    color: white;
}

/* Interactive Map Container */
.interactive-map {
    height: 500px;
    border-radius: var(--radius-lg);
    overflow: hidden;
    margin: var(--space-8) 0;
    box-shadow: var(--shadow-lg);
}

/* Video Container */
.video-container {
    position: relative;
    width: 100%;
    padding-bottom: 56.25%; /* 16:9 aspect ratio */
    height: 0;
    margin: var(--space-6) 0;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
}

.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: var(--radius-lg);
}

/* Quiz Feedback Enhanced */
.quiz-feedback.correct {
    background: var(--color-success-bg);
    border-left: 4px solid var(--color-success-border);
}

.quiz-feedback.incorrect {
    background: rgba(239, 68, 68, 0.1);
    border-left: 4px solid #ef4444;
}

.feedback-correct {
    color: var(--color-success-border);
    font-weight: 500;
    margin: 0;
}

.feedback-incorrect {
    color: #dc2626;
    font-weight: 500;
    margin: 0;
}

/* Responsive adjustments */
@media (max-width: 640px) {
    .term {
        grid-template-columns: 1fr;
    }
    
    .chapter-nav {
        flex-direction: column;
        gap: var(--space-4);
    }
    
    .chapter-nav-link {
        justify-content: center;
    }
}