:root {
    --primary-color: #1a365d;
    --secondary-color: #2c5282;
    --accent-color: #3182ce;
    --light-bg: #f7fafc;
    --text-color: #2d3748;
    --text-muted: #718096;
    --border-color: #e2e8f0;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: var(--text-color);
    line-height: 1.6;
}

.navbar {
    background-color: #fff;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    padding: 15px 0;
}

.navbar-brand {
    font-weight: 700;
    font-size: 1.5rem;
    color: var(--primary-color) !important;
}

.navbar-nav .nav-link {
    color: var(--text-color) !important;
    font-weight: 500;
    margin: 0 10px;
    transition: all 0.3s ease;
}

.navbar-nav .nav-link:hover,
.navbar-nav .nav-link.active {
    color: var(--accent-color) !important;
}

.btn-contact {
    background-color: var(--primary-color);
    color: white;
    border-radius: 4px;
    padding: 8px 20px;
    font-weight: 500;
    transition: all 0.3s ease;
}

.btn-contact:hover {
    background-color: var(--secondary-color);
    color: white;
}

.hero-section {
    padding: 120px 0 80px;
    background-color: #fff;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.section-title {
    font-size: 1.8rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 25px;
    position: relative;
    padding-bottom: 10px;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 3px;
    background-color: var(--accent-color);
}

.about-content p {
    margin-bottom: 20px;
    font-size: 1.05rem;
    color: var(--text-color);
}

.profile-img {
    max-width: 100%;
    border-radius: 8px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.categories-section {
    padding: 80px 0;
    background-color: var(--light-bg);
}

.category-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    height: 100%;
}

.category-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.15);
}

.category-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    font-size: 2rem;
    color: white;
}

.category-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.category-stats {
    margin-top: 1rem;
    font-size: 0.9rem;
    color: var(--text-muted);
}

.page-header {
    padding: 100px 0 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    text-align: center;
}

.page-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
}

.page-description {
    font-size: 1.2rem;
    opacity: 0.9;
    max-width: 800px;
    margin: 0 auto;
}

.filter-section, .series-selector, .year-selector {
    padding: 40px 0;
    background-color: white;
    border-bottom: 1px solid var(--border-color);
}

.filter-buttons, .series-tabs {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.filter-btn, .series-tab {
    padding: 0.5rem 1.5rem;
    background: var(--light-bg);
    border: 2px solid var(--border-color);
    color: var(--text-color);
    border-radius: 50px;
    font-weight: 500;
    transition: all 0.3s ease;
    cursor: pointer;
}

.filter-btn.active, .series-tab.active,
.filter-btn:hover, .series-tab:hover {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.year-dropdown {
    max-width: 200px;
    margin: 0 auto;
}

.articles-grid {
    padding: 60px 0;
    background-color: var(--light-bg);
}

.article-card {
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
    transition: all 0.3s ease;
    height: 100%;
}

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

.article-image {
    position: relative;
    height: 200px;
    overflow: hidden;
}

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

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

.article-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(to bottom, transparent, rgba(0,0,0,0.7));
    display: flex;
    align-items: flex-end;
    padding: 1rem;
}

.article-category, .article-series {
    background: var(--accent-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
}

.article-content {
    padding: 1.5rem;
}

.article-content h3 {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.article-content p {
    color: var(--text-muted);
    margin-bottom: 1rem;
    font-size: 0.95rem;
}

.article-meta {
    display: flex;
    justify-content: space-between;
    margin-bottom: 1rem;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.article-header {
    padding: 1rem 1.5rem;
    background: var(--light-bg);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.article-quarter {
    background: var(--accent-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-weight: 500;
}

.article-year {
    color: var(--text-muted);
    font-weight: 500;
}

.article-tags {
    margin-bottom: 1rem;
}

.tag {
    background: var(--light-bg);
    color: var(--text-muted);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.8rem;
    margin-right: 0.5rem;
}

.recent-section {
    padding: 60px 0;
    background-color: white;
}

.contact-section {
    padding: 80px 0;
    background-color: var(--light-bg);
}

.contact-form {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.08);
}

.form-control, .form-select {
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 0.75rem 1rem;
    margin-bottom: 1rem;
    transition: all 0.3s ease;
}

.form-control:focus, .form-select:focus {
    border-color: var(--accent-color);
    box-shadow: 0 0 0 0.2rem rgba(49, 130, 206, 0.25);
}

.btn-submit {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 0.75rem 2rem;
    font-weight: 500;
    border-radius: 8px;
    transition: all 0.3s ease;
}

.btn-submit:hover {
    background-color: var(--secondary-color);
}

.contact-info {
    margin-top: 2rem;
}

.contact-item {
    display: flex;
    align-items: center;
    margin-bottom: 1.5rem;
}

.contact-icon {
    width: 50px;
    height: 50px;
    background-color: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-right: 1rem;
}

footer {
    background-color: var(--primary-color);
    color: white;
    padding: 50px 0 20px;
}

.footer-links {
    list-style: none;
    padding: 0;
}

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

.footer-links a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-links a:hover {
    color: white;
}

.social-icons a {
    display: inline-block;
    width: 40px;
    height: 40px;
    background-color: rgba(255, 255, 255, 0.1);
    color: white;
    border-radius: 50%;
    text-align: center;
    line-height: 40px;
    margin-right: 10px;
    transition: all 0.3s ease;
}

.social-icons a:hover {
    background-color: rgba(255, 255, 255, 0.2);
    transform: translateY(-3px);
}

.copyright {
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
    color: rgba(255, 255, 255, 0.7);
}

@media (max-width: 768px) {
    .hero-title {
        font-size: 2.2rem;
    }
    
    .page-title {
        font-size: 2rem;
    }
    
    .navbar-nav {
        margin-top: 1rem;
    }
    
    .btn-contact {
        margin-top: 0.5rem;
        width: 100%;
    }
    
    .filter-buttons, .series-tabs {
        justify-content: flex-start;
        overflow-x: auto;
        padding-bottom: 0.5rem;
    }
}