/* Learn Hub - Homepage Styles */

/* ========================================
   CSS VARIABLES
   ======================================== */
:root {
    --color-bg: #0a0a0f;
    --color-bg-elevated: #12121a;
    --color-bg-card: rgba(255, 255, 255, 0.03);
    
    --primary-500: #0ea5e9;
    --primary-400: #38bdf8;
    --accent-cyan: #06b6d4;
    --accent-blue: #3b82f6;
    --accent-sky: #0284c7;
    
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --text-tertiary: #64748b;
    
    --border-color: rgba(255, 255, 255, 0.08);
    --border-hover: rgba(255, 255, 255, 0.15);
    
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
    
    --radius-lg: 16px;
    --radius-xl: 24px;
    
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
}

/* Light Theme */
body.light-theme {
    --color-bg: #f8fafc;
    --color-bg-elevated: #ffffff;
    --color-bg-card: rgba(255, 255, 255, 0.8);
    
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-tertiary: #64748b;
    
    --border-color: rgba(0, 0, 0, 0.08);
    --border-hover: rgba(0, 0, 0, 0.15);
    
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

/* ========================================
   RESET & BASE
   ======================================== */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background-color: var(--color-bg);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

/* ========================================
   AMBIENT BACKGROUND
   ======================================== */
.ambient-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
    overflow: hidden;
}

.gradient-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.4;
    animation: float 20s infinite ease-in-out;
}

.orb-1 {
    width: 600px;
    height: 600px;
    background: linear-gradient(135deg, var(--primary-500), var(--accent-purple));
    top: -200px;
    right: -200px;
    animation-delay: 0s;
}

.orb-2 {
    width: 500px;
    height: 500px;
    background: linear-gradient(135deg, var(--accent-cyan), var(--primary-400));
    bottom: -150px;
    left: -150px;
    animation-delay: -7s;
}

.orb-3 {
    width: 400px;
    height: 400px;
    background: linear-gradient(135deg, var(--accent-pink), var(--accent-purple));
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    animation-delay: -14s;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    25% { transform: translate(30px, -30px) scale(1.05); }
    50% { transform: translate(-20px, 20px) scale(0.95); }
    75% { transform: translate(20px, 10px) scale(1.02); }
}

/* ========================================
   HEADER
   ======================================== */
.glass-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(10, 10, 15, 0.8);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
}

body.light-theme .glass-header {
    background: rgba(248, 250, 252, 0.8);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1.5rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-icon {
    font-size: 1.75rem;
}

.logo-title {
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--text-primary), var(--primary-400));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.theme-toggle {
    width: 44px;
    height: 44px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    background: var(--color-bg-card);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.theme-toggle:hover {
    background: var(--border-color);
    color: var(--text-primary);
}

.theme-toggle svg {
    width: 20px;
    height: 20px;
}

.sun-icon { display: none; }
body.light-theme .sun-icon { display: block; }
body.light-theme .moon-icon { display: none; }

/* ========================================
   HERO SECTION
   ======================================== */
.hub-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 3rem 2rem;
}

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

.hero h1 {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--text-primary), var(--primary-300));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
}

/* ========================================
   FEATURES GRID
   ======================================== */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

.feature-card {
    display: flex;
    flex-direction: column;
    background: var(--color-bg-card);
    backdrop-filter: blur(20px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    padding: 2rem;
    text-decoration: none;
    color: inherit;
    transition: all var(--transition-base);
    box-shadow: var(--shadow-lg);
}

.feature-card:hover {
    transform: translateY(-4px);
    border-color: var(--border-hover);
    box-shadow: 0 20px 40px -10px rgba(0, 0, 0, 0.6);
}

.feature-card:hover .feature-link {
    color: var(--accent-cyan);
}

.feature-icon-wrapper {
    width: 80px;
    height: 80px;
    border-radius: 20px;
    background: linear-gradient(135deg, var(--primary-500), var(--accent-purple));
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
}

.feature-icon {
    font-size: 2.5rem;
}

.feature-content h2 {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.feature-description {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.feature-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: auto;
}

.feature-tag {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    padding: 0.4rem 0.8rem;
    background: rgba(99, 102, 241, 0.15);
    color: var(--primary-400);
    border-radius: 9999px;
}

.feature-link {
    font-weight: 600;
    color: var(--text-secondary);
    transition: color var(--transition-fast);
}

/* ========================================
   FOOTER
   ======================================== */
.glass-footer {
    text-align: center;
    padding: 2rem;
    background: rgba(10, 10, 15, 0.5);
    backdrop-filter: blur(10px);
    border-top: 1px solid var(--border-color);
    color: var(--text-tertiary);
    font-size: 0.875rem;
}

body.light-theme .glass-footer {
    background: rgba(248, 250, 252, 0.5);
}

/* ========================================
   MOBILE RESPONSIVE
   ======================================== */
@media (max-width: 768px) {
    .header-content {
        padding: 1rem 1.5rem;
    }
    
    .hub-container {
        padding: 2rem 1.5rem;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .feature-card {
        padding: 1.5rem;
    }
    
    .feature-icon-wrapper {
        width: 64px;
        height: 64px;
    }
    
    .feature-icon {
        font-size: 2rem;
    }
    
    .feature-content h2 {
        font-size: 1.5rem;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 1.75rem;
    }
    
    .features-grid {
        gap: 1rem;
    }
    
    .feature-card {
        padding: 1.25rem;
    }
}