/* ==========================================
   VARIABLES & RESET
   ========================================== */
:root {
    /* Colors */
    --primary: #4F46E5;
    --primary-dark: #4338CA;
    --primary-light: #818CF8;
    --secondary: #10B981;
    --accent: #F59E0B;
    --danger: #EF4444;
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-success: linear-gradient(135deg, #10B981 0%, #059669 100%);
    --gradient-warning: linear-gradient(135deg, #F59E0B 0%, #D97706 100%);
    
    /* Light Theme */
    --bg-primary: #FFFFFF;
    --bg-secondary: #F9FAFB;
    --bg-tertiary: #F3F4F6;
    --text-primary: #111827;
    --text-secondary: #6B7280;
    --text-muted: #9CA3AF;
    --border: #E5E7EB;
    --shadow: rgba(0, 0, 0, 0.1);
    --shadow-lg: rgba(0, 0, 0, 0.15);
    
    /* Typography */
    --font-primary: 'Poppins', sans-serif;
    --font-secondary: 'Inter', sans-serif;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.5rem;
    --radius-md: 1rem;
    --radius-lg: 1.5rem;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition: all 0.3s ease;
}

/* Dark Theme */
body.dark-theme {
    --bg-primary: #111827;
    --bg-secondary: #1F2937;
    --bg-tertiary: #374151;
    --text-primary: #F9FAFB;
    --text-secondary: #D1D5DB;
    --text-muted: #9CA3AF;
    --border: #374151;
    --shadow: rgba(0, 0, 0, 0.3);
    --shadow-lg: rgba(0, 0, 0, 0.5);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-secondary);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ==========================================
   NAVIGATION
   ========================================== */
.navbar {
    background: var(--bg-primary);
    box-shadow: 0 2px 10px var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: var(--transition);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.5rem;
    font-weight: 700;
    font-family: var(--font-primary);
    color: var(--primary);
}

.nav-logo i {
    font-size: 1.8rem;
}

.nav-menu {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
}

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-sm);
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary);
    background: rgba(79, 70, 229, 0.1);
}

.nav-actions {
    display: flex;
    gap: var(--spacing-sm);
    align-items: center;
}

.theme-toggle,
.nav-toggle {
    background: var(--bg-secondary);
    border: none;
    width: 40px;
    height: 40px;
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
    color: var(--text-primary);
}

.theme-toggle:hover,
.nav-toggle:hover {
    background: var(--bg-tertiary);
    transform: scale(1.05);
}

.nav-toggle {
    display: none;
}

/* ==========================================
   HERO SECTION
   ========================================== */
.hero {
    padding: var(--spacing-xl) var(--spacing-md);
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    align-items: center;
    min-height: 80vh;
    max-width: 1200px;
    margin: 0 auto;
}

.hero-content h1 {
    font-size: 3.5rem;
    font-weight: 700;
    font-family: var(--font-primary);
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
}

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

.hero-subtitle {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
}

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

.btn {
    padding: 0.875rem 1.75rem;
    border-radius: var(--radius-md);
    text-decoration: none;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: 0 4px 15px rgba(79, 70, 229, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(79, 70, 229, 0.4);
}

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: var(--bg-tertiary);
}

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

.btn-light:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(255, 255, 255, 0.3);
}

/* Hero Image with Floating Cards */
.hero-image {
    position: relative;
    height: 400px;
}

.floating-card {
    position: absolute;
    background: white;
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    box-shadow: 0 10px 30px var(--shadow-lg);
    display: flex;
    align-items: center;
    gap: 1rem;
    animation: float 3s ease-in-out infinite;
}

.floating-card i {
    font-size: 2rem;
    color: var(--primary);
}

.floating-card span {
    font-weight: 600;
    color: var(--text-primary);
}

.card-1 {
    top: 10%;
    left: 10%;
    animation-delay: 0s;
}

.card-2 {
    top: 40%;
    right: 10%;
    animation-delay: 1s;
}

.card-3 {
    bottom: 10%;
    left: 20%;
    animation-delay: 2s;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-20px); }
}

/* ==========================================
   STATS SECTION
   ========================================== */
.stats {
    padding: var(--spacing-xl) var(--spacing-md);
    background: var(--bg-secondary);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.stat-card {
    background: var(--bg-primary);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    text-align: center;
    box-shadow: 0 4px 15px var(--shadow);
    transition: var(--transition);
}

.stat-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px var(--shadow-lg);
}

.stat-icon {
    font-size: 3rem;
    color: var(--primary);
    margin-bottom: var(--spacing-sm);
}

.stat-number {
    font-size: 3rem;
    font-weight: 700;
    color: var(--primary);
    font-family: var(--font-primary);
}

.stat-label {
    color: var(--text-secondary);
    font-size: 1rem;
}

/* ==========================================
   FEATURES SECTION
   ========================================== */
.features {
    padding: var(--spacing-xl) var(--spacing-md);
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    font-family: var(--font-primary);
    margin-bottom: var(--spacing-sm);
}

.section-subtitle {
    text-align: center;
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
}

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

.feature-card {
    background: var(--bg-secondary);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    transition: var(--transition);
    border: 2px solid transparent;
}

.feature-card:hover {
    transform: translateY(-5px);
    border-color: var(--primary);
    box-shadow: 0 8px 25px var(--shadow-lg);
}

.feature-icon {
    width: 60px;
    height: 60px;
    background: var(--gradient-primary);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-md);
}

.feature-icon i {
    font-size: 1.8rem;
    color: white;
}

.feature-card h3 {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    font-family: var(--font-primary);
}

.feature-card p {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ==========================================
   TOPICS SECTION
   ========================================== */
.topics {
    padding: var(--spacing-xl) var(--spacing-md);
    background: var(--bg-secondary);
}

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

.topic-card {
    background: var(--bg-primary);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    text-decoration: none;
    color: var(--text-primary);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.topic-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--gradient-primary);
    transform: scaleX(0);
    transition: var(--transition);
}

.topic-card:hover::before {
    transform: scaleX(1);
}

.topic-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px var(--shadow-lg);
}

.topic-icon {
    width: 50px;
    height: 50px;
    background: rgba(79, 70, 229, 0.1);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-sm);
}

.topic-icon i {
    font-size: 1.5rem;
    color: var(--primary);
}

.topic-card h3 {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
    font-family: var(--font-primary);
}

.topic-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-sm);
}

.topic-badge {
    display: inline-block;
    background: var(--gradient-primary);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-full);
    font-size: 0.85rem;
    font-weight: 500;
}

/* ==========================================
   CTA SECTION
   ========================================== */
.cta {
    padding: var(--spacing-xl) var(--spacing-md);
    background: var(--gradient-primary);
    text-align: center;
}

.cta-content h2 {
    color: white;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    font-family: var(--font-primary);
}

.cta-content p {
    color: rgba(255, 255, 255, 0.9);
    font-size: 1.2rem;
    margin-bottom: var(--spacing-lg);
}

/* ==========================================
   FOOTER
   ========================================== */
.footer {
    background: var(--bg-secondary);
    padding: var(--spacing-xl) var(--spacing-md) var(--spacing-lg);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.footer-section h3 {
    font-size: 1.3rem;
    margin-bottom: var(--spacing-sm);
    font-family: var(--font-primary);
}

.footer-section h4 {
    font-size: 1.1rem;
    margin-bottom: var(--spacing-sm);
    font-family: var(--font-primary);
}

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

.footer-section ul {
    list-style: none;
}

.footer-section li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: var(--transition);
}

.footer-section a:hover {
    color: var(--primary);
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--border);
    color: var(--text-secondary);
}

/* ==========================================
   RESPONSIVE
   ========================================== */
@media (max-width: 968px) {
    .hero {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-content h1 {
        font-size: 2.5rem;
    }
    
    .hero-image {
        display: none;
    }
    
    .hero-buttons {
        justify-content: center;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: var(--bg-primary);
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 27px var(--shadow);
        padding: var(--spacing-lg);
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .hero-content h1 {
        font-size: 2rem;
    }
    
    .features-grid,
    .topics-grid {
        grid-template-columns: 1fr;
    }
}