/* ============================================
   PHYSICAL GEOGRAPHY HUB PAGE
   Complete standalone styles for index.html
   ============================================ */

/* CSS Variables */
:root {
    /* Colors */
    --primary: #6366f1;
    --primary-dark: #4338ca;
    --primary-light: #818cf8;
    --primary-glow: rgba(99, 102, 241, 0.5);
    
    --accent: #f59e0b;
    --accent-pink: #ec4899;
    --accent-green: #10b981;
    
    /* Backgrounds */
    --bg-dark: #0f172a;
    --bg-darker: #020617;
    --bg-card: rgba(30, 41, 59, 0.8);
    --bg-card-hover: rgba(51, 65, 85, 0.9);
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
    
    /* Text */
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    
    /* Gradients */
    --gradient-hero: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-card: linear-gradient(135deg, rgba(99, 102, 241, 0.1) 0%, rgba(236, 72, 153, 0.1) 100%);
    
    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 8px 32px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 20px 60px rgba(0, 0, 0, 0.3);
    --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.4);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.5rem;
    --radius-md: 1rem;
    --radius-lg: 1.5rem;
    --radius-xl: 2rem;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Poppins', -apple-system, BlinkMacSystemFont, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--bg-darker);
    min-height: 100vh;
    overflow-x: hidden;
}

a {
    color: inherit;
    text-decoration: none;
}

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

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* ============================================
   PRELOADER
   ============================================ */
.preloader {
    position: fixed;
    inset: 0;
    background: var(--bg-darker);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    transition: opacity 0.5s, visibility 0.5s;
}

.preloader.hidden {
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
}

.preloader-content {
    text-align: center;
}

.globe-loader {
    margin-bottom: 1.5rem;
}

.globe {
    font-size: 5rem;
    animation: spin 2s linear infinite;
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.preloader-text {
    font-size: 1.25rem;
    color: var(--text-secondary);
    background: var(--gradient-hero);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* ============================================
   NAVIGATION
   ============================================ */
.main-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(15, 23, 42, 0.9);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--glass-border);
    z-index: 1000;
    transition: var(--transition-base);
}

.main-nav.scrolled {
    background: rgba(15, 23, 42, 0.98);
    box-shadow: var(--shadow-md);
}

.main-nav.hidden {
    transform: translateY(-100%);
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-weight: 800;
    font-size: 1.5rem;
}

.logo-icon {
    font-size: 2rem;
}

.logo-text {
    background: var(--gradient-hero);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.25rem;
    border-radius: var(--radius-full);
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.9375rem;
    transition: var(--transition-base);
}

.nav-link:hover {
    color: var(--text-primary);
    background: var(--glass-bg);
}

.nav-link.active {
    background: var(--gradient-hero);
    color: white;
    box-shadow: var(--shadow-glow);
}

.nav-icon {
    font-size: 1.25rem;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.theme-toggle {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--bg-card);
    border: 1px solid var(--glass-border);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-base);
}

.theme-toggle:hover {
    background: var(--gradient-hero);
    transform: scale(1.1);
}

.theme-icon {
    font-size: 1.25rem;
}

.mobile-menu-toggle {
    display: none;
    width: 44px;
    height: 44px;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 5px;
    background: var(--bg-card);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-md);
}

.hamburger {
    width: 24px;
    height: 3px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: var(--transition-base);
}

/* Mobile Menu */
.mobile-menu {
    position: fixed;
    top: 70px;
    left: 0;
    right: 0;
    background: var(--bg-dark);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--glass-border);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
    z-index: 999;
}

.mobile-menu.active {
    max-height: 400px;
}

.mobile-menu-content {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.mobile-nav-link {
    padding: 1rem 1.5rem;
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    color: var(--text-secondary);
    font-weight: 500;
    transition: var(--transition-base);
}

.mobile-nav-link:hover,
.mobile-nav-link.active {
    background: var(--gradient-hero);
    color: white;
}

/* ============================================
   HERO SECTION
   ============================================ */
.hero-section {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    inset: 0;
    z-index: 1;
}

.hero-image {
    width: 100%;
    height: 100%;
    object-fit: cover;
    animation: slowZoom 30s ease-in-out infinite alternate;
}

@keyframes slowZoom {
    from { transform: scale(1); }
    to { transform: scale(1.1); }
}

.hero-overlay {
    position: absolute;
    inset: 0;
    background: linear-gradient(
        180deg,
        rgba(2, 6, 23, 0.7) 0%,
        rgba(15, 23, 42, 0.5) 50%,
        rgba(2, 6, 23, 0.9) 100%
    );
}

.hero-particles {
    position: absolute;
    inset: 0;
    pointer-events: none;
}

.hero-content {
    position: relative;
    z-index: 2;
    text-align: center;
    max-width: 1000px;
    padding: 0 2rem;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1.5rem;
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-full);
    margin-bottom: 2rem;
}

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

.badge-text {
    font-weight: 600;
    color: var(--text-secondary);
}

.hero-title {
    font-size: clamp(2.5rem, 8vw, 5rem);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 1.5rem;
}

.title-line {
    display: block;
}

.title-highlight {
    background: var(--gradient-hero);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.title-emoji {
    display: inline-block;
    animation: bounce 2s ease-in-out infinite;
}

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

.hero-subtitle {
    font-size: clamp(1rem, 2.5vw, 1.5rem);
    color: var(--text-secondary);
    margin-bottom: 3rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

/* Hero Stats */
.hero-stats {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 3rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.stat-item {
    text-align: center;
}

.stat-number {
    font-size: 3rem;
    font-weight: 800;
    background: var(--gradient-hero);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-plus {
    font-size: 2rem;
    font-weight: 800;
    background: var(--gradient-hero);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    display: block;
    font-size: 0.875rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-top: 0.5rem;
}

.stat-divider {
    width: 1px;
    height: 50px;
    background: var(--glass-border);
}

/* Hero Actions */
.hero-actions {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1.5rem;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    padding: 1rem 2rem;
    border-radius: var(--radius-full);
    font-weight: 700;
    font-size: 1rem;
    transition: var(--transition-base);
}

.btn-primary {
    background: var(--gradient-hero);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-glow);
}

.btn-secondary {
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    color: var(--text-primary);
    border: 1px solid var(--glass-border);
}

.btn-secondary:hover {
    background: var(--bg-card);
    border-color: var(--primary);
    transform: translateY(-3px);
}

/* Scroll Indicator */
.scroll-indicator {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    text-align: center;
    z-index: 2;
}

.mouse {
    width: 26px;
    height: 40px;
    border: 2px solid var(--text-secondary);
    border-radius: 20px;
    margin: 0 auto 0.75rem;
    position: relative;
}

.wheel {
    width: 4px;
    height: 8px;
    background: var(--text-secondary);
    border-radius: 2px;
    position: absolute;
    top: 8px;
    left: 50%;
    transform: translateX(-50%);
    animation: scroll 2s infinite;
}

@keyframes scroll {
    0%, 100% { opacity: 0; top: 8px; }
    50% { opacity: 1; top: 18px; }
}

.scroll-indicator span {
    font-size: 0.75rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

/* ============================================
   INTRO SECTION
   ============================================ */
.intro-section {
    padding: 5rem 0;
    background: var(--bg-dark);
}

.intro-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2rem;
}

.intro-card {
    text-align: center;
    padding: 2rem;
    background: var(--bg-card);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-xl);
    transition: var(--transition-base);
}

.intro-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.intro-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.intro-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.intro-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ============================================
   TOPICS SECTION
   ============================================ */
.topics-main {
    padding: 6rem 0;
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-badge {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    background: var(--gradient-card);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-full);
    font-weight: 600;
    font-size: 0.875rem;
    color: var(--primary-light);
    margin-bottom: 1.5rem;
}

.section-title {
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 800;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* Topics Grid */
.topics-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.topic-card {
    position: relative;
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    overflow: hidden;
    border: 1px solid var(--glass-border);
    transition: var(--transition-slow);
    display: block;
}

.topic-card:hover {
    transform: translateY(-10px) scale(1.02);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
    border-color: var(--primary);
}

.topic-image {
    position: relative;
    height: 200px;
    overflow: hidden;
}

.topic-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition-slow);
}

.topic-card:hover .topic-image img {
    transform: scale(1.1);
}

.topic-overlay {
    position: absolute;
    inset: 0;
    background: linear-gradient(to bottom, transparent 30%, rgba(0, 0, 0, 0.8) 100%);
}

.topic-icon {
    position: absolute;
    top: 1rem;
    right: 1rem;
    font-size: 2.5rem;
    z-index: 2;
    filter: drop-shadow(0 2px 10px rgba(0,0,0,0.5));
}

.topic-content {
    padding: 1.5rem;
}

.topic-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.topic-desc {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.topic-sections {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.section-tag {
    padding: 0.375rem 0.75rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--text-muted);
    transition: var(--transition-base);
}

.topic-card:hover .section-tag {
    background: var(--primary);
    color: white;
    border-color: transparent;
}

.topic-arrow {
    position: absolute;
    bottom: 1.5rem;
    right: 1.5rem;
    width: 40px;
    height: 40px;
    background: var(--gradient-hero);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    color: white;
    opacity: 0;
    transform: translateX(-10px);
    transition: var(--transition-base);
}

.topic-card:hover .topic-arrow {
    opacity: 1;
    transform: translateX(0);
}

/* ============================================
   QUICK CONCEPTS SECTION
   ============================================ */
.quick-concepts-section {
    padding: 6rem 0;
    background: var(--bg-dark);
}

.concepts-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
}

.concept-card {
    padding: 2rem;
    background: var(--bg-card);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-xl);
    transition: var(--transition-base);
}

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

.concept-icon {
    font-size: 3rem;
    margin-bottom: 1.5rem;
}

.concept-card h3 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.concept-points {
    margin-bottom: 1.5rem;
}

.concept-points p {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 0.5rem;
}

.concept-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--primary-light);
    font-weight: 600;
    transition: var(--transition-base);
}

.concept-link:hover {
    gap: 1rem;
}

/* ============================================
   EXPLORE FEATURES SECTION
   ============================================ */
.explore-features-section {
    padding: 6rem 0;
}

.features-links {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 1.5rem;
}

.feature-link-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    padding: 2rem 1.5rem;
    background: var(--bg-card);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-xl);
    transition: var(--transition-base);
    text-align: center;
}

.feature-link-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.feature-emoji {
    font-size: 3rem;
}

.feature-name {
    font-weight: 700;
    color: var(--text-primary);
}

.feature-count {
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* ============================================
   FOOTER
   ============================================ */
.main-footer {
    background: var(--bg-dark);
    border-top: 1px solid var(--glass-border);
    margin-top: 4rem;
}

.footer-top {
    padding: 4rem 0 2rem;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr repeat(3, 1fr);
    gap: 3rem;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

.footer-tagline {
    color: var(--text-secondary);
    line-height: 1.7;
}

.footer-links h4 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.footer-links ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.footer-links a {
    color: var(--text-secondary);
    transition: var(--transition-base);
}

.footer-links a:hover {
    color: var(--primary-light);
    padding-left: 5px;
}

.footer-bottom {
    border-top: 1px solid var(--glass-border);
    padding: 2rem 0;
}

.footer-bottom .container {
    display: flex;
    justify-content: center;
}

.copyright {
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* ============================================
   BACK TO TOP
   ============================================ */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background: var(--gradient-hero);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    box-shadow: var(--shadow-md);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: var(--transition-base);
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

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

/* ============================================
   RESPONSIVE
   ============================================ */
@media (max-width: 1200px) {
    .topics-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .features-links {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .footer-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 900px) {
    .intro-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .concepts-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .topics-grid {
        grid-template-columns: 1fr;
    }
    
    .intro-grid {
        grid-template-columns: 1fr;
    }
    
    .features-links {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .hero-stats {
        gap: 2rem;
    }
    
    .stat-number {
        font-size: 2.5rem;
    }
    
    .stat-divider {
        display: none;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .features-links {
        grid-template-columns: 1fr;
    }
    
    .hero-actions {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
}