body {
    font-family: 'Poppins', sans-serif;
}
.lang-vi {
    display: none;
}
.language-active {
    background-color: #4f46e5;
    color: white;
}
.blog-content h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin: 2rem 0 1rem 0;
    color: #1f2937;
}
.blog-content h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin: 1.5rem 0 0.75rem 0;
    color: #374151;
}
.blog-content p {
    margin-bottom: 1rem;
    line-height: 1.7;
    color: #4b5563;
}
.blog-content ul, .blog-content ol {
    margin: 1rem 0;
    padding-left: 2rem;
}
.blog-content li {
    margin-bottom: 0.5rem;
    line-height: 1.6;
    color: #4b5563;
}
.blog-content blockquote {
    border-left: 4px solid #4f46e5;
    padding-left: 1rem;
    margin: 1.5rem 0;
    font-style: italic;
    color: #6b7280;
    background-color: #f9fafb;
    padding: 1rem;
    border-radius: 0.5rem;
}
.blog-content img {
    border-radius: 0.75rem;
    margin: 1.5rem 0;
    box-shadow: 0 10px 25px -3px rgba(0, 0, 0, 0.1);
}
.social-share-btn {
    transition: all 0.3s ease;
}
.social-share-btn:hover {
    transform: translateY(-2px);
}
.related-post-card {
    transition: all 0.3s ease;
}
.related-post-card:hover {
    transform: translateY(-5px);
}
.comment-card {
    transition: all 0.3s ease;
}
.comment-card:hover {
    background-color: #f9fafb;
}
.progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    width: 0%;
    height: 3px;
    background: linear-gradient(90deg, #4f46e5, #7c3aed);
    z-index: 9999;
    transition: width 0.3s ease;
}
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background: #4f46e5;
    color: white;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 50;
}
.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}
.back-to-top:hover {
    background: #3730a3;
    transform: translateY(-2px);
}

/* Mobile Optimizations */
@media (max-width: 1024px) {
    .floating-toc {
        display: none;
    }
}

@media (max-width: 768px) {
    .blog-content h2 {
        font-size: 1.375rem;
        margin: 1.5rem 0 0.75rem 0;
    }
    
    .blog-content h3 {
        font-size: 1.125rem;
        margin: 1.25rem 0 0.5rem 0;
    }
    
    .blog-content p {
        font-size: 0.9rem;
        line-height: 1.6;
    }
    
    .blog-content blockquote {
        margin: 1rem 0;
        padding: 0.75rem;
        font-size: 0.9rem;
    }
    
    .social-share-btn {
        padding: 0.5rem 0.75rem;
        font-size: 0.875rem;
    }
    
    .social-share-btn span {
        display: none;
    }
    
    .social-share-btn i {
        margin-right: 0;
    }
    
    .back-to-top {
        bottom: 1rem;
        right: 1rem;
        width: 45px;
        height: 45px;
    }
    
    .comment-card {
        padding: 1rem;
    }
    
    .related-post-card {
        padding: 1rem;
    }
}

@media (max-width: 640px) {
    .container {
        padding-left: 1rem;
        padding-right: 1rem;
    }
    
    .blog-content {
        padding: 1rem;
    }
    
    .blog-content h2 {
        font-size: 1.25rem;
    }
    
    .blog-content h3 {
        font-size: 1.125rem;
    }
    
    .blog-content ul, .blog-content ol {
        padding-left: 1.5rem;
    }
    
    .social-share-btn {
        padding: 0.5rem;
        min-width: 44px;
        justify-content: center;
    }
    
    .floating-toc {
        display: none;
    }
}

/* Article Header Mobile Optimization */
@media (max-width: 768px) {
    .article-header h1 {
        font-size: 1.5rem;
        line-height: 1.3;
    }
    
    .article-meta {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }
    
    .article-meta > div {
        flex-wrap: wrap;
        gap: 0.5rem;
    }
}

/* Sidebar Mobile Optimization */
@media (max-width: 1024px) {
    .sidebar-section {
        margin-bottom: 1.5rem;
    }
}

/* Comment Section Mobile */
@media (max-width: 768px) {
    .comment-form .grid {
        grid-template-columns: 1fr;
    }
    
    .comment-avatar {
        width: 2rem;
        height: 2rem;
    }
    
    .comment-content {
        font-size: 0.875rem;
    }
}

/* Newsletter Mobile */
@media (max-width: 640px) {
    .newsletter-form {
        padding: 1rem;
    }
    
    .newsletter-form h3 {
        font-size: 1.125rem;
    }
    
    .newsletter-form p {
        font-size: 0.875rem;
    }
}

/* Tags Mobile */
@media (max-width: 640px) {
    .tags-container {
        gap: 0.25rem;
    }
    
    .tag {
        font-size: 0.75rem;
        padding: 0.25rem 0.5rem;
    }
}

/* Featured Image Mobile */
@media (max-width: 768px) {
    .featured-image {
        height: 200px;
    }
    
    .featured-image-overlay {
        padding: 1rem;
    }
    
    .featured-image h1 {
        font-size: 1.25rem;
        line-height: 1.3;
    }
}

/* Breadcrumb Mobile */
@media (max-width: 640px) {
    .breadcrumb {
        font-size: 0.75rem;
        padding: 0.5rem 0;
    }
}

/* Language Switcher Mobile */
@media (max-width: 640px) {
    .language-switcher {
        top: 1rem;
        right: 1rem;
        padding: 0.25rem;
    }
    
    .language-switcher button {
        padding: 0.25rem 0.5rem;
        font-size: 0.75rem;
    }
}

/* Footer Mobile */
@media (max-width: 768px) {
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
        text-align: center;
    }
    
    .footer-section h3 {
        font-size: 1rem;
    }
    
    .footer-links {
        justify-content: center;
    }
}

/* Utility Classes for Mobile */
.mobile-hidden {
    display: block;
}

@media (max-width: 768px) {
    .mobile-hidden {
        display: none;
    }
}

.mobile-only {
    display: none;
}

@media (max-width: 768px) {
    .mobile-only {
        display: block;
    }
}

/* Touch Targets */
@media (max-width: 768px) {
    button, a, input, textarea {
        min-height: 44px;
    }
    
    .social-share-btn {
        min-width: 44px;
        min-height: 44px;
    }
}

/* Improved Readability on Mobile */
@media (max-width: 640px) {
    .blog-content {
        font-size: 16px; /* Prevents zoom on iOS */
    }
    
    .blog-content p {
        margin-bottom: 1.25rem;
    }
    
    .blog-content img {
        margin: 1rem 0;
        border-radius: 0.5rem;
    }
}

@media (max-width: 1280px) {
    .floating-toc {
        display: none;
    }
}

.sidebar-toc {
    background: white;
    border-radius: 0.75rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    padding: 1.5rem;
    margin-bottom: 2rem;
}

.sidebar-toc a {
    display: block;
    padding: 0.5rem 0;
    color: #6b7280;
    text-decoration: none;
    border-bottom: 1px solid #e5e7eb;
    transition: color 0.3s ease;
    font-size: 0.875rem;
}

.sidebar-toc a:hover,
.sidebar-toc a.active {
    color: #4f46e5;
}

.sidebar-toc a:last-child {
    border-bottom: none;
}