/* Base styles and CSS reset */
:root {
    --primary-color: #121b22;
    --secondary-color: #232e36;
    --accent-color: #4ff8d2;
    --accent-hover: #88ffe4;
    --text-color: #fafafa;
    --text-muted: #a0aec0;
    --card-bg: #293945;
    --success-green: #a4df95;
    --transparent-bg: rgba(18, 27, 34, 0.8);
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --transition-base: 0.2s ease-in-out;
    --container-width: 1200px;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen,
        Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--primary-color);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Container */
.container {
    width: 100%;
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Header and Navigation */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background-color: var(--transparent-bg);
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(10px);
}

.navbar {
    height: 4rem;
}

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

.nav-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-color);
    text-decoration: none;
    text-shadow: 0 0 10px rgba(79, 248, 210, 0.3);
}

.nav-links {
    display: flex;
    gap: var(--spacing-md);
}

.nav-link {
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    transition: color var(--transition-base);
    position: relative;
}

.nav-link:hover {
    color: var(--accent-color);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--accent-color);
    transition: width var(--transition-base);
}

.nav-link:hover::after {
    width: 100%;
}

/* Mobile menu button */
.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
}

/* Hero Section */
.hero {
    padding: calc(4rem + var(--spacing-xl)) 0 var(--spacing-xl);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at top right, 
                               rgba(79, 248, 210, 0.1), 
                               transparent 70%);
}

.hero-content {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
    position: relative;
}

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

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-muted);
    margin-bottom: var(--spacing-lg);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 600;
    transition: all var(--transition-base);
    cursor: pointer;
    border: none;
    font-size: 1rem;
}

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

.primary-btn:hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 0 15px rgba(79, 248, 210, 0.3);
}

.secondary-btn {
    background-color: transparent;
    border: 2px solid var(--accent-color);
    color: var(--accent-color);
}

.secondary-btn:hover {
    background-color: rgba(79, 248, 210, 0.1);
    transform: translateY(-2px);
}

.cta-buttons {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    margin-top: var(--spacing-lg);
}

/* Stats Section */
.stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
    text-align: center;
}

.stat-item {
    padding: var(--spacing-md);
    background-color: rgba(255, 255, 255, 0.05);
    border-radius: 0.5rem;
    backdrop-filter: blur(10px);
}

.stat-number {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-color);
    margin-bottom: var(--spacing-xs);
}

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

/* Featured Books Section */
.featured-books {
    padding: var(--spacing-xl) 0;
    background-color: var(--secondary-color);
}

.featured-books h2 {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    font-size: 2rem;
}

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

.book-card {
    background-color: var(--card-bg);
    border-radius: 1rem;
    overflow: hidden;
    transition: transform var(--transition-base), 
                box-shadow var(--transition-base);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.book-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.book-card-inner {
    display: flex;
    flex-direction: column;
    height: 100%;
}

.book-image-container {
    position: relative;
    padding-top: 133%; /* 4:3 aspect ratio */
    overflow: hidden;
}

.book-image {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-base);
}

.book-card:hover .book-image {
    transform: scale(1.05);
}

.book-category {
    position: absolute;
    top: var(--spacing-sm);
    right: var(--spacing-sm);
    background-color: var(--accent-color);
    color: var(--primary-color);
    padding: 0.25rem 0.75rem;
    border-radius: 2rem;
    font-size: 0.875rem;
    font-weight: 600;
}

.book-info {
    padding: var(--spacing-md);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    flex: 1;
}

.book-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-color);
    margin: 0;
}

.book-author {
    font-size: 0.875rem;
    color: var(--accent-color);
    margin: 0;
}

.book-description {
    font-size: 0.875rem;
    color: var(--text-muted);
    line-height: 1.5;
    margin: 0;
    flex: 1;
}

.book-btn {
    margin-top: var(--spacing-sm);
    width: 100%;
}

/* Newsletter Section */
.newsletter {
    padding: var(--spacing-xl) 0;
    background-color: var(--primary-color);
}

.newsletter-content {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
}

.newsletter h2 {
    margin-bottom: var(--spacing-sm);
}

.newsletter p {
    color: var(--text-muted);
    margin-bottom: var(--spacing-lg);
}

.newsletter-form .form-group {
    display: flex;
    gap: var(--spacing-sm);
    max-width: 500px;
    margin: 0 auto;
}

.newsletter-form input {
    flex: 1;
    padding: 0.75rem 1rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 0.5rem;
    background-color: rgba(255, 255, 255, 0.05);
    color: var(--text-color);
    font-size: 1rem;
}

.newsletter-form input:focus {
    outline: none;
    border-color: var(--accent-color);
}

/* Footer */
.footer {
    background-color: var(--secondary-color);
    padding-top: var(--spacing-xl);
}

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

.footer-section h3 {
    color: var(--text-color);
    margin-bottom: var(--spacing-md);
}

.footer-section p {
    color: var(--text-muted);
}

.footer-nav {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.footer-nav a {
    color: var(--text-muted);
    text-decoration: none;
    transition: color var(--transition-base);
}

.footer-nav a:hover {
    color: var(--accent-color);
}

.social-links {
    display: flex;
    gap: var(--spacing-md);
}

.social-links a {
    color: var(--text-muted);
    font-size: 1.5rem;
    transition: color var(--transition-base);
}

.social-links a:hover {
    color: var(--accent-color)
}