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

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #fafafa;
}

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

/* Header */
.header {
    background: #fff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.nav-brand h1 {
    color: #667eea;
    font-size: 1.8rem;
    font-weight: 700;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-menu a {
    text-decoration: none;
    color: #555;
    font-weight: 500;
    transition: color 0.3s ease;
    position: relative;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: #667eea;
}

.nav-menu a.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    right: 0;
    height: 2px;
    background: #667eea;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: #333;
    margin: 3px 0;
    transition: 0.3s;
}

/* Main Content */
.main {
    margin-top: 80px;
}

/* Hero Section */
.hero-section {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 4rem 0;
    text-align: center;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.hero-subtitle {
    font-size: 1.2rem;
    opacity: 0.9;
    max-width: 600px;
    margin: 0 auto;
}

/* Blog Section */
.blog-section {
    padding: 4rem 0;
}

.blog-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 3rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.blog-header h2 {
    font-size: 2.5rem;
    color: #333;
    font-weight: 600;
}

.blog-filters {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 0.5rem 1.5rem;
    border: 2px solid #e0e0e0;
    background: white;
    color: #666;
    border-radius: 25px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 500;
}

.filter-btn:hover,
.filter-btn.active {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

/* Blog Grid */
.blog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.blog-card {
    background: white;
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.blog-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}

.blog-image {
    position: relative;
    overflow: hidden;
}

.blog-image img {
    width: 100%;
    height: 250px;
    object-fit: cover;
    transition: transform 0.3s ease;
}

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

.blog-category {
    position: absolute;
    top: 1rem;
    left: 1rem;
    background: rgba(102, 126, 234, 0.9);
    color: white;
    padding: 0.3rem 1rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
}

.blog-content {
    padding: 1.5rem;
}

.blog-title {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 0.8rem;
    color: #333;
    line-height: 1.4;
}

.blog-excerpt {
    color: #666;
    margin-bottom: 1rem;
    line-height: 1.6;
}

.blog-meta {
    display: flex;
    gap: 1rem;
    margin-bottom: 1rem;
    font-size: 0.9rem;
    color: #888;
}

.blog-meta i {
    margin-right: 0.3rem;
}

.read-more {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: #667eea;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.read-more:hover {
    color: #5a67d8;
}

.read-more i {
    transition: transform 0.3s ease;
}

.read-more:hover i {
    transform: translateX(3px);
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
}

.pagination-btn {
    padding: 0.8rem 1rem;
    border: 1px solid #e0e0e0;
    background: white;
    color: #666;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    min-width: 45px;
}

.pagination-btn:hover:not(:disabled) {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

.pagination-btn.active {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

.pagination-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* Footer */
.footer {
    background: #2d3748;
    color: white;
    padding: 3rem 0 1rem;
}

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

.footer-section h3,
.footer-section h4 {
    margin-bottom: 1rem;
    color: #667eea;
}

.footer-section p {
    color: #a0aec0;
    line-height: 1.6;
}

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

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

.footer-section ul li a {
    color: #a0aec0;
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-section ul li a:hover {
    color: #667eea;
}

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

.social-links a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: #4a5568;
    color: white;
    border-radius: 50%;
    text-decoration: none;
    transition: all 0.3s ease;
}

.social-links a:hover {
    background: #667eea;
    transform: translateY(-2px);
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #4a5568;
    color: #a0aec0;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .blog-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .blog-header h2 {
        font-size: 2rem;
    }
    
    .blog-grid {
        grid-template-columns: 1fr;
    }
    
    .blog-filters {
        width: 100%;
        justify-content: center;
    }
    
    .container {
        padding: 0 15px;
    }
    
    .nav {
        padding: 1rem;
    }
}

@media (max-width: 480px) {
    .hero-section {
        padding: 2rem 0;
    }
    
    .blog-section {
        padding: 2rem 0;
    }
    
    .blog-card {
        margin: 0 10px;
    }
    
    .filter-btn {
        padding: 0.4rem 1rem;
        font-size: 0.9rem;
    }
}

/* Animation cho filter */
.blog-card {
    animation: fadeIn 0.5s ease-in-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

/* Loading state */
.loading {
    opacity: 0.6;
    pointer-events: none;
}