:root {
    --primary: #2563eb;
    --secondary: #64748b;
    --dark: #0f172a;
    --light: #f8fafc;
    --accent: #3b82f6;
    --text: #334155;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    color: var(--text);
    background-color: var(--light);
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Header & Nav */
header {
    background: white;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-weight: 800;
    font-size: 1.25rem;
    color: var(--dark);
    text-transform: uppercase;
    letter-spacing: 1px;
}

nav ul {
    display: flex;
    list-style: none;
}

nav ul li {
    margin-left: 2rem;
}

nav ul li a {
    text-decoration: none;
    color: var(--secondary);
    font-weight: 500;
    transition: color 0.3s;
}

nav ul li a:hover {
    color: var(--primary);
}

/* Hero Section */
#hero {
    display: flex;
    align-items: center;
    padding: 5rem 2rem;
    gap: 4rem;
}

.hero-content {
    flex: 1;
}

h1 {
    font-size: 3.5rem;
    color: var(--dark);
    line-height: 1.1;
    margin-bottom: 1rem;
}

.subtitle {
    font-size: 1.5rem;
    color: var(--primary);
    font-weight: 600;
    margin-bottom: 1.5rem;
}

.description {
    font-size: 1.125rem;
    margin-bottom: 2rem;
    color: var(--secondary);
}

/* Book Cover Placeholder */
.hero-image {
    flex: 1;
    display: flex;
    justify-content: center;
}

.book-placeholder {
    width: 300px;
    height: 450px;
    background: var(--dark);
    border-radius: 8px;
    box-shadow: 20px 20px 60px rgba(0,0,0,0.2);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: bold;
    transform: rotate(3deg);
    transition: transform 0.3s;
    border-left: 15px solid #1e293b;
}

.book-placeholder:hover {
    transform: rotate(0deg) scale(1.02);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s;
}

.btn-primary {
    background: var(--primary);
    color: white;
    margin-right: 1rem;
}

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

.btn:hover {
    opacity: 0.9;
    transform: translateY(-2px);
}

/* Grid Section */
.bg-alt {
    background: #f1f5f9;
    padding: 5rem 0;
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}

.card i {
    font-size: 2.5rem;
    color: var(--primary);
    margin-bottom: 1.5rem;
}

.card h3 {
    margin-bottom: 1rem;
    color: var(--dark);
}

/* Footer */
footer {
    padding: 3rem 0;
    text-align: center;
    border-top: 1px solid #e2e8f0;
}

.social-links {
    margin-top: 1rem;
}

.social-links a {
    color: var(--secondary);
    font-size: 1.5rem;
    margin: 0 0.5rem;
}

@media (max-width: 768px) {
    #hero {
        flex-direction: column;
        text-align: center;
    }
    h1 {
        font-size: 2.5rem;
    }
}