/* Reset và Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: #333;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
.header {
    background: #fff;
    box-shadow: 0 2px 20px rgba(0,0,0,0.1);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    transition: all 0.3s ease;
}

.header .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 20px;
}

.nav-brand {
    display: flex;
    align-items: center;
    font-size: 1.5rem;
    font-weight: 700;
    color: #2563eb;
    text-decoration: none;
}

.nav-brand i {
    margin-right: 0.5rem;
    font-size: 1.8rem;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 2rem;
}

.nav-link {
    text-decoration: none;
    color: #64748b;
    font-weight: 500;
    transition: color 0.3s ease;
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: #2563eb;
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    right: 0;
    height: 2px;
    background: #2563eb;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.search-box {
    position: relative;
    display: flex;
    align-items: center;
}

.search-box input {
    padding: 0.5rem 2.5rem 0.5rem 1rem;
    border: 2px solid #e2e8f0;
    border-radius: 25px;
    outline: none;
    transition: border-color 0.3s ease;
    min-width: 250px;
}

.search-box input:focus {
    border-color: #2563eb;
}

.search-box i {
    position: absolute;
    right: 1rem;
    color: #64748b;
    cursor: pointer;
}

.cart-icon {
    position: relative;
    cursor: pointer;
    padding: 0.5rem;
    color: #64748b;
    transition: color 0.3s ease;
}

.cart-icon:hover {
    color: #2563eb;
}

.cart-count {
    position: absolute;
    top: -5px;
    right: -5px;
    background: #ef4444;
    color: white;
    border-radius: 50%;
    width: 20px;
    height: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: 600;
}

/* Hero Section */
.hero {
    padding: 120px 0 80px;
    background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
    min-height: 80vh;
    display: flex;
    align-items: center;
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-content h1 {
    font-size: 3.5rem;
    font-weight: 700;
    color: #1e293b;
    margin-bottom: 1.5rem;
    line-height: 1.2;
}

.hero-content p {
    font-size: 1.25rem;
    color: #64748b;
    margin-bottom: 2rem;
    line-height: 1.6;
}

.cta-button {
    background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
    color: white;
    border: none;
    padding: 1rem 2rem;
    border-radius: 50px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(37, 99, 235, 0.3);
}

.hero-image {
    position: relative;
}

.hero-image img {
    width: 100%;
    height: 400px;
    object-fit: cover;
    border-radius: 20px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.1);
}

/* Section Titles */
.section-title {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    color: #1e293b;
    margin-bottom: 3rem;
}

/* Categories Section */
.categories {
    padding: 80px 0;
    background: #fff;
}

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

.category-card {
    background: #fff;
    padding: 2rem;
    border-radius: 20px;
    text-align: center;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
    cursor: pointer;
    border: 2px solid transparent;
}

.category-card:hover {
    transform: translateY(-10px);
    border-color: #2563eb;
    box-shadow: 0 20px 40px rgba(37, 99, 235, 0.2);
}

.category-card i {
    font-size: 3rem;
    color: #2563eb;
    margin-bottom: 1rem;
}

.category-card h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #1e293b;
}

.category-card p {
    color: #64748b;
    font-size: 0.95rem;
}

/* Books Section */
.books {
    padding: 80px 0;
    background: #f8fafc;
}

.filter-buttons {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 0.75rem 1.5rem;
    border: 2px solid #e2e8f0;
    background: #fff;
    color: #64748b;
    border-radius: 25px;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.3s ease;
}

.filter-btn:hover,
.filter-btn.active {
    background: #2563eb;
    color: white;
    border-color: #2563eb;
}

.books-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 2rem;
}

.book-card {
    background: #fff;
    border-radius: 20px;
    overflow: hidden;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
    cursor: pointer;
}

.book-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 40px rgba(0,0,0,0.15);
}

.book-image {
    position: relative;
    overflow: hidden;
    height: 300px;
}

.book-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.3s ease;
}

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

.book-badge {
    position: absolute;
    top: 1rem;
    left: 1rem;
    background: #ef4444;
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.75rem;
    font-weight: 600;
}

.book-info {
    padding: 1.5rem;
}

.book-category {
    color: #2563eb;
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 0.5rem;
}

.book-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: #1e293b;
    margin-bottom: 0.5rem;
    line-height: 1.3;
}

.book-author {
    color: #64748b;
    font-size: 0.95rem;
    margin-bottom: 1rem;
}

.book-price {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 1rem;
}

.price-current {
    font-size: 1.5rem;
    font-weight: 700;
    color: #2563eb;
}

.price-old {
    color: #94a3b8;
    text-decoration: line-through;
    font-size: 1rem;
}

.add-to-cart {
    width: 100%;
    background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
    color: white;
    border: none;
    padding: 0.75rem;
    border-radius: 10px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.add-to-cart:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(37, 99, 235, 0.3);
}

/* About Section */
.about {
    padding: 80px 0;
    background: #fff;
}

.about-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 4rem;
    align-items: center;
}

.about-text h2 {
    font-size: 2.5rem;
    font-weight: 700;
    color: #1e293b;
    margin-bottom: 1.5rem;
}

.about-text p {
    font-size: 1.1rem;
    color: #64748b;
    margin-bottom: 2rem;
    line-height: 1.7;
}

.features {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.feature {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem;
    background: #f8fafc;
    border-radius: 10px;
}

.feature i {
    font-size: 1.5rem;
    color: #2563eb;
}

.about-stats {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.stat {
    text-align: center;
    padding: 2rem;
    background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
    color: white;
    border-radius: 20px;
}

.stat h3 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.stat p {
    font-size: 1.1rem;
    opacity: 0.9;
}

/* Contact Section */
.contact {
    padding: 80px 0;
    background: #f8fafc;
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    margin-bottom: 2rem;
}

.contact-item i {
    font-size: 1.5rem;
    color: #2563eb;
    margin-top: 0.25rem;
}

.contact-item h4 {
    font-size: 1.1rem;
    font-weight: 600;
    color: #1e293b;
    margin-bottom: 0.25rem;
}

.contact-item p {
    color: #64748b;
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.contact-form input,
.contact-form textarea {
    padding: 1rem;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    outline: none;
    transition: border-color 0.3s ease;
    font-family: inherit;
}

.contact-form input:focus,
.contact-form textarea:focus {
    border-color: #2563eb;
}

.contact-form button {
    background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
    color: white;
    border: none;
    padding: 1rem;
    border-radius: 10px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.contact-form button:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(37, 99, 235, 0.3);
}

/* Cart Sidebar */
.cart-sidebar {
    position: fixed;
    top: 0;
    right: -400px;
    width: 400px;
    height: 100vh;
    background: #fff;
    box-shadow: -10px 0 30px rgba(0,0,0,0.1);
    z-index: 2000;
    transition: right 0.3s ease;
    display: flex;
    flex-direction: column;
}

.cart-sidebar.open {
    right: 0;
}

.cart-header {
    padding: 2rem;
    border-bottom: 1px solid #e2e8f0;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.cart-header h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: #1e293b;
}

.close-cart {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: #64748b;
    cursor: pointer;
    transition: color 0.3s ease;
}

.close-cart:hover {
    color: #ef4444;
}

.cart-items {
    flex: 1;
    padding: 1rem;
    overflow-y: auto;
}

.cart-item {
    display: flex;
    gap: 1rem;
    padding: 1rem;
    border-bottom: 1px solid #f1f5f9;
}

.cart-item-image {
    width: 60px;
    height: 80px;
    object-fit: cover;
    border-radius: 5px;
}

.cart-item-info {
    flex: 1;
}

.cart-item-title {
    font-weight: 600;
    color: #1e293b;
    margin-bottom: 0.25rem;
    font-size: 0.9rem;
}

.cart-item-price {
    color: #2563eb;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.cart-item-controls {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.qty-btn {
    background: #f1f5f9;
    border: none;
    width: 25px;
    height: 25px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    transition: background 0.3s ease;
}

.qty-btn:hover {
    background: #e2e8f0;
}

.qty-input {
    width: 40px;
    text-align: center;
    border: 1px solid #e2e8f0;
    border-radius: 5px;
    padding: 0.25rem;
}

.cart-footer {
    padding: 2rem;
    border-top: 1px solid #e2e8f0;
}

.cart-total {
    margin-bottom: 1rem;
    font-size: 1.25rem;
    text-align: center;
}

.checkout-btn {
    width: 100%;
    background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
    color: white;
    border: none;
    padding: 1rem;
    border-radius: 10px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.checkout-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(37, 99, 235, 0.3);
}

.cart-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.5);
    z-index: 1500;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
}

.cart-overlay.open {
    opacity: 1;
    visibility: visible;
}

.empty-cart {
    text-align: center;
    padding: 2rem;
    color: #64748b;
}

/* Footer */
.footer {
    background: #1e293b;
    color: #e2e8f0;
    padding: 4rem 0 2rem;
}

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

.footer-brand {
    display: flex;
    align-items: center;
    font-size: 1.5rem;
    font-weight: 700;
    color: #2563eb;
    margin-bottom: 1rem;
}

.footer-brand i {
    margin-right: 0.5rem;
    font-size: 1.8rem;
}

.footer-section p {
    margin-bottom: 1rem;
    line-height: 1.6;
    color: #94a3b8;
}

.footer-section h4 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: #fff;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section ul li a {
    color: #94a3b8;
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-section ul li a:hover {
    color: #2563eb;
}

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

.social-links a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: #334155;
    color: #94a3b8;
    border-radius: 50%;
    text-decoration: none;
    transition: all 0.3s ease;
}

.social-links a:hover {
    background: #2563eb;
    color: white;
    transform: translateY(-2px);
}

.payment-methods {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
}

.payment-methods i {
    font-size: 2rem;
    color: #94a3b8;
    transition: color 0.3s ease;
}

.payment-methods i:hover {
    color: #2563eb;
}

.footer-bottom {
    border-top: 1px solid #334155;
    padding-top: 2rem;
    text-align: center;
    color: #94a3b8;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .nav-menu {
        display: none;
    }
    
    .hero .container {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-content h1 {
        font-size: 2.5rem;
    }
    
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .contact-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .search-box input {
        min-width: 200px;
    }
    
    .hero-content h1 {
        font-size: 2rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .categories-grid {
        grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    }
    
    .books-grid {
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    }
    
    .cart-sidebar {
        width: 100%;
        right: -100%;
    }
    
    .filter-buttons {
        gap: 0.5rem;
    }
    
    .filter-btn {
        padding: 0.5rem 1rem;
        font-size: 0.9rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .header .container {
        padding: 0.75rem 15px;
    }
    
    .nav-actions {
        gap: 0.5rem;
    }
    
    .search-box input {
        min-width: 150px;
    }
    
    .hero {
        padding: 100px 0 60px;
    }
    
    .hero-content h1 {
        font-size: 1.75rem;
    }
    
    .hero-content p {
        font-size: 1rem;
    }
    
    .categories-grid {
        grid-template-columns: 1fr;
    }
    
    .books-grid {
        grid-template-columns: 1fr;
    }
    
    .book-card {
        max-width: 300px;
        margin: 0 auto;
    }
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.book-card {
    animation: fadeInUp 0.6s ease forwards;
}

.book-card:nth-child(even) {
    animation-delay: 0.1s;
}

.book-card:nth-child(3n) {
    animation-delay: 0.2s;
}

/* Smooth scrolling */
html {
    scroll-behavior: smooth;
}

/* Loading states */
.loading {
    opacity: 0.7;
    pointer-events: none;
}

.btn-loading {
    position: relative;
    color: transparent;
}

.btn-loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 20px;
    height: 20px;
    border: 2px solid transparent;
    border-top: 2px solid currentColor;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to {
        transform: translate(-50%, -50%) rotate(360deg);
    }
}