/* Modern CSS Reset & Custom Styling for Central Product Hub */
:root {
    --bg-dark: #020617;
    --bg-slate: #0f172a;
    --bg-card: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    
    --primary: #3b82f6;
    --primary-light: #60a5fa;
    --accent: #06b6d4;
    --accent-light: #22d3ee;
    --success: #10b981;
    --success-light: #34d399;
    
    --font-sans: 'Inter', sans-serif;
    --font-display: 'Outfit', sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
    
    --border-color: rgba(255, 255, 255, 0.08);
    --border-glow: rgba(59, 130, 246, 0.25);
}

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

html {
    scroll-behavior: smooth;
    background-color: var(--bg-dark);
    color: var(--text-primary);
    font-family: var(--font-sans);
    overflow-x: hidden;
}

body {
    overflow-x: hidden;
    position: relative;
    line-height: 1.6;
}

/* Background Glow Effects */
.bg-glow-1 {
    position: absolute;
    width: 600px;
    height: 600px;
    top: -200px;
    right: -100px;
    background: radial-gradient(circle, rgba(59, 130, 246, 0.15) 0%, rgba(0, 0, 0, 0) 70%);
    z-index: -1;
    pointer-events: none;
}

.bg-glow-2 {
    position: absolute;
    width: 500px;
    height: 500px;
    top: 800px;
    left: -200px;
    background: radial-gradient(circle, rgba(6, 182, 212, 0.12) 0%, rgba(0, 0, 0, 0) 70%);
    z-index: -1;
    pointer-events: none;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Navigation */
header {
    background: rgba(2, 6, 23, 0.7);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 72px;
}

.logo {
    font-family: var(--font-display);
    font-size: 22px;
    font-weight: 800;
    color: var(--text-primary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 8px;
}

.logo span {
    background: linear-gradient(135deg, var(--primary-light) 0%, var(--accent-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-links {
    display: flex;
    gap: 32px;
    list-style: none;
    align-items: center;
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 14.5px;
    font-weight: 500;
    transition: color 0.2s ease;
}

.nav-links a:hover {
    color: var(--text-primary);
}

/* Hero Section */
.hero {
    padding-top: 160px;
    padding-bottom: 60px;
    text-align: center;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: rgba(59, 130, 246, 0.1);
    border: 1px solid rgba(59, 130, 246, 0.2);
    color: var(--primary-light);
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 12.5px;
    font-weight: 600;
    margin-bottom: 24px;
    letter-spacing: 0.5px;
}

.hero-title {
    font-family: var(--font-display);
    font-size: 56px;
    font-weight: 800;
    line-height: 1.1;
    letter-spacing: -1.5px;
    margin-bottom: 24px;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.hero-title span {
    background: linear-gradient(135deg, var(--primary-light) 0%, var(--accent-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-description {
    color: var(--text-secondary);
    font-size: 18px;
    margin-bottom: 36px;
    max-width: 680px;
    margin-left: auto;
    margin-right: auto;
}

/* Showcase Section */
.showcase {
    padding: 60px 0 100px 0;
}

.product-list {
    display: flex;
    flex-direction: column;
    gap: 48px;
}

.product-row {
    background: rgba(30, 41, 59, 0.3);
    border: 1px solid var(--border-color);
    border-radius: 24px;
    padding: 48px;
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: 48px;
    align-items: center;
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

.product-row:hover {
    background: rgba(30, 41, 59, 0.55);
    border-color: rgba(59, 130, 246, 0.25);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
}

.product-meta {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    height: 100%;
}

.product-badge-row {
    display: flex;
    gap: 8px;
    margin-bottom: 16px;
}

.product-badge {
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
    padding: 4px 10px;
    border-radius: 12px;
    color: #ffffff;
}

.badge-active {
    background-color: var(--success);
}

.badge-soon {
    background-color: var(--primary);
}

.badge-hot {
    background-color: #ef4444;
}

.product-title {
    font-family: var(--font-display);
    font-size: 28px;
    font-weight: 800;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.product-desc {
    color: var(--text-secondary);
    font-size: 15px;
    margin-bottom: 24px;
}

.product-highlights {
    display: flex;
    gap: 16px;
    margin-bottom: 32px;
    flex-wrap: wrap;
}

.highlight-item {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13.5px;
    color: var(--text-primary);
}

.highlight-item svg {
    color: var(--accent-light);
}

.product-pricing-ctas {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid var(--border-color);
    padding-top: 24px;
    flex-wrap: wrap;
    gap: 20px;
}

.product-price {
    font-family: var(--font-display);
    font-size: 28px;
    font-weight: 800;
    color: var(--text-primary);
}

.product-price span {
    font-size: 13.5px;
    color: var(--text-secondary);
    font-weight: 400;
    display: block;
}

.ctas-group {
    display: flex;
    gap: 12px;
}

/* 3D Book Mockups */
.book-container {
    perspective: 1000px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.book {
    width: 180px;
    height: 250px;
    position: relative;
    transform-style: preserve-3d;
    transform: rotateY(-15deg) rotateX(10deg);
    transition: transform 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

.product-row:hover .book {
    transform: rotateY(-25deg) rotateX(12deg) scale(1.05);
}

.book-cover {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    border-radius: 2px 6px 6px 2px;
    box-shadow: 10px 10px 25px rgba(0, 0, 0, 0.5);
    z-index: 5;
    background-size: cover;
    background-position: center;
}

.book-spine {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    width: 15px;
    background: #0f172a;
    border-radius: 2px 0 0 2px;
    transform: rotateY(-90deg);
    transform-origin: right;
    z-index: 6;
}

/* Specific Cover Styling */
.cover-interview {
    background-image: url('cover.png');
}

.cover-compose {
    background-image: url('cover-compose.png');
}

.cover-design {
    background-image: url('cover-system-design.png');
}

.cover-performance {
    background-image: url('cover-performance.png');
}

.cover-security {
    background-image: url('cover-security.png');
}

.cover-compose-canvas {
    background-image: url('cover-compose-canvas.png');
}

.cover-kotlin-concurrency {
    background-image: url('cover-kotlin-concurrency.png');
}

.cover-badge {
    font-size: 8px;
    font-weight: 700;
    text-transform: uppercase;
    color: var(--accent-light);
    letter-spacing: 1px;
}

.cover-title {
    font-family: var(--font-display);
    font-size: 15px;
    font-weight: 800;
    color: white;
    line-height: 1.2;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 20px;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.btn-primary {
    background: linear-gradient(135deg, var(--success) 0%, #047857 100%);
    color: white;
    border: none;
    box-shadow: 0 4px 15px rgba(16, 185, 129, 0.25);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(16, 185, 129, 0.4);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.08);
    border-color: rgba(255, 255, 255, 0.15);
    transform: translateY(-2px);
}

.btn-disabled {
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid rgba(255, 255, 255, 0.03);
    color: var(--text-muted);
    cursor: not-allowed;
}

/* About Author Section */
.about {
    border-top: 1px solid var(--border-color);
    padding: 80px 0;
    background: rgba(15, 23, 42, 0.4);
}

.about-card {
    display: grid;
    grid-template-columns: 0.8fr 1.2fr;
    gap: 60px;
    align-items: center;
}

.about-left {
    text-align: center;
}

.author-avatar {
    width: 140px;
    height: 140px;
    border-radius: 50%;
    border: 3px solid var(--accent-light);
    margin-bottom: 20px;
    box-shadow: 0 0 20px rgba(6, 182, 212, 0.2);
}

.author-name {
    font-family: var(--font-display);
    font-size: 24px;
    font-weight: 700;
    color: var(--text-primary);
}

.author-title {
    color: var(--text-muted);
    font-size: 14px;
    font-weight: 500;
}

.about-right h2 {
    font-family: var(--font-display);
    font-size: 32px;
    font-weight: 800;
    margin-bottom: 16px;
    letter-spacing: -1px;
}

.about-right p {
    color: var(--text-secondary);
    font-size: 15.5px;
    margin-bottom: 16px;
}

.author-portfolio-link {
    display: inline-flex;
    align-items: center;
    color: var(--accent-light);
    text-decoration: none;
    font-family: var(--font-display);
    font-size: 15px;
    font-weight: 600;
    margin-top: 8px;
    transition: all 0.2s ease;
}

.author-portfolio-link:hover {
    color: var(--primary-light);
}

.author-portfolio-link:hover svg {
    transform: translateX(4px);
}

/* Footer */
footer {
    border-top: 1px solid var(--border-color);
    padding: 40px 0;
    text-align: center;
    color: var(--text-muted);
    font-size: 13.5px;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 24px;
    list-style: none;
    margin: 16px 0;
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.2s ease;
}

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

/* Responsive Grid Adjustments */
@media (max-width: 868px) {
    .product-row {
        grid-template-columns: 1fr;
        padding: 30px;
        gap: 30px;
        text-align: center;
    }
    
    .book-container {
        margin-bottom: 12px;
    }
    
    .product-highlights {
        justify-content: center;
    }
    
    .product-pricing-ctas {
        justify-content: center;
        flex-direction: column;
        gap: 16px;
    }
    
    .about-card {
        grid-template-columns: 1fr;
        gap: 30px;
        text-align: center;
    }
}