:root {
    --primary-color: #1e3a8a;
    --secondary-color: #3b82f6;
    --accent-color: #06b6d4;
    --text-dark: #1f2937;
    --text-light: #6b7280;
    --bg-light: #f8fafc;
    --bg-white: #ffffff;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --gradient-primary: linear-gradient(135deg, #1e3a8a 0%, #3b82f6 100%);
    --gradient-accent: linear-gradient(135deg, #06b6d4 0%, #0891b2 100%);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
}

.navbar-brand {
    font-weight: 700;
    font-size: 1.5rem;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.navbar {
    background: var(--bg-white) !important;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    padding: 1rem 0;
}

.btn-primary {
    background: var(--gradient-primary);
    border: none;
    padding: 12px 30px;
    font-weight: 600;
    border-radius: 8px;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(59, 130, 246, 0.3);
}

.btn-outline-primary {
    border: 2px solid var(--secondary-color);
    color: var(--secondary-color);
    padding: 10px 25px;
    font-weight: 600;
    border-radius: 8px;
    transition: all 0.3s ease;
}

.btn-outline-primary:hover {
    background: var(--secondary-color);
    transform: translateY(-1px);
}

.hero {
    background: var(--gradient-primary);
    color: white;
    padding: 120px 0;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><defs><pattern id="grid" width="10" height="10" patternUnits="userSpaceOnUse"><path d="M 10 0 L 0 0 0 10" fill="none" stroke="rgba(255,255,255,0.1)" stroke-width="0.5"/></pattern></defs><rect width="100" height="100" fill="url(%23grid)"/></svg>');
    opacity: 0.3;
}

.hero-content {
    position: relative;
    z-index: 2;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    line-height: 1.2;
}

.hero .lead {
    font-size: 1.3rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.book-card {
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    transition: all 0.3s ease;
    overflow: hidden;
    height: 100%;
}

.book-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 40px rgba(0,0,0,0.1);
    border-color: var(--secondary-color);
}

.book-cover {
    width: 100%;
    height: 300px;
    background: var(--gradient-accent);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
}

.book-cover::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(45deg, rgba(255,255,255,0.1) 25%, transparent 25%, transparent 75%, rgba(255,255,255,0.1) 75%),
                linear-gradient(45deg, rgba(255,255,255,0.1) 25%, transparent 25%, transparent 75%, rgba(255,255,255,0.1) 75%);
    background-size: 20px 20px;
    background-position: 0 0, 10px 10px;
}

.book-cover i {
    font-size: 4rem;
    color: white;
    z-index: 2;
    position: relative;
}

.book-info {
    padding: 1.5rem;
}

.book-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.book-author {
    color: var(--text-light);
    margin-bottom: 1rem;
}

.book-price {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--success-color);
    margin-bottom: 1rem;
}

.book-description {
    color: var(--text-light);
    margin-bottom: 1.5rem;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.section {
    padding: 80px 0;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-dark);
}

.section-subtitle {
    text-align: center;
    color: var(--text-light);
    font-size: 1.1rem;
    margin-bottom: 4rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.about {
    background: var(--bg-light);
}

.stats {
    background: var(--bg-white);
    border-radius: 16px;
    padding: 2rem;
    text-align: center;
    box-shadow: 0 4px 20px rgba(0,0,0,0.08);
}

.stats h3 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--secondary-color);
    margin-bottom: 0.5rem;
}

.stats p {
    color: var(--text-light);
    margin: 0;
}

.footer {
    background: var(--text-dark);
    color: white;
    padding: 3rem 0 1rem;
}

.footer h5 {
    color: var(--accent-color);
    margin-bottom: 1rem;
}

.footer a {
    color: #9ca3af;
    text-decoration: none;
    transition: color 0.3s ease;
}

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

@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .hero .lead {
        font-size: 1.1rem;
    }
    
    .section {
        padding: 60px 0;
    }
    
    .section-title {
        font-size: 2rem;
    }
}

.loading {
    opacity: 0.7;
    pointer-events: none;
}

.success-message {
    background: var(--success-color);
    color: white;
    padding: 1rem;
    border-radius: 8px;
    margin-top: 1rem;
    display: none;
}

.modal-content {
    border: none;
    border-radius: 16px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.2);
}

.modal-header {
    background: var(--gradient-primary);
    color: white;
    border-radius: 16px 16px 0 0;
}

#card-element {
    padding: 12px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    margin: 1rem 0;
}

#card-element.StripeElement--focus {
    border-color: var(--secondary-color);
}