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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f8f9fa;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 60px 20px;
}

.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
}

.nav-logo h2 {
    color: #fff;
    font-size: 1.5rem;
}

.nav-links {
    display: flex;
    list-style: none;
}

.nav-links li {
    margin-left: 30px;
}

.nav-links a {
    color: #fff;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-links a:hover {
    color: #4ade80;
}

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

.hamburger span {
    width: 25px;
    height: 3px;
    background: #fff;
    margin: 3px 0;
}

.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    text-align: center;
    color: #fff;
    padding-top: 80px;
}

.profile-img {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    object-fit: cover;
    border: 5px solid rgba(255, 255, 255, 0.3);
    margin-bottom: 20px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 10px;
}

.hero h2 {
    font-size: 1.5rem;
    font-weight: 400;
    margin-bottom: 10px;
    opacity: 0.9;
}

.affiliation {
    font-size: 1.1rem;
    opacity: 0.85;
    margin-bottom: 30px;
}

.social-links {
    display: flex;
    justify-content: center;
    gap: 20px;
}

.social-icon {
    width: 45px;
    height: 45px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    font-size: 1.2rem;
    transition: all 0.3s ease;
    text-decoration: none;
}

.social-icon:hover {
    background: #fff;
    color: #667eea;
    transform: translateY(-5px);
}

.section-title {
    font-size: 2.2rem;
    text-align: center;
    margin-bottom: 50px;
    color: #2d3748;
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 2px;
}

.about {
    background: #fff;
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
    font-size: 1.1rem;
    color: #555;
    text-align: center;
}

.about-content p {
    margin-bottom: 20px;
}

.education {
    background: #f8f9fa;
}

.timeline {
    max-width: 800px;
    margin: 0 auto;
}

.timeline-item {
    position: relative;
    padding-left: 50px;
    margin-bottom: 40px;
    border-left: 3px solid #667eea;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: -10px;
    top: 0;
    width: 17px;
    height: 17px;
    border-radius: 50%;
    background: #667eea;
    border: 3px solid #fff;
    box-shadow: 0 0 10px rgba(102, 126, 234, 0.5);
}

.timeline-content {
    background: #fff;
    padding: 25px;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.08);
}

.timeline-content h3 {
    color: #2d3748;
    font-size: 1.3rem;
    margin-bottom: 8px;
}

.degree {
    color: #667eea;
    font-weight: 600;
    margin-bottom: 5px;
}

.period {
    color: #888;
    font-size: 0.9rem;
    margin-bottom: 10px;
}

.description {
    color: #555;
}

.research {
    background: #fff;
}

.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.research-card {
    background: linear-gradient(135deg, #f8f9fa 0%, #fff 100%);
    padding: 35px;
    border-radius: 15px;
    text-align: center;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid #e2e8f0;
}

.research-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.1);
}

.research-icon {
    width: 70px;
    height: 70px;
    border-radius: 50%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    font-size: 1.8rem;
    color: #fff;
}

.research-card h3 {
    color: #2d3748;
    font-size: 1.2rem;
    margin-bottom: 10px;
}

.research-card p {
    color: #666;
    font-size: 0.95rem;
}

.publications {
    background: #f8f9fa;
}

.publication-list {
    max-width: 900px;
    margin: 0 auto;
}

.publication-item {
    background: #fff;
    padding: 30px;
    border-radius: 12px;
    margin-bottom: 25px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.06);
    transition: transform 0.3s ease;
}

.publication-item:hover {
    transform: translateX(5px);
}

.publication-item h3 {
    color: #2d3748;
    font-size: 1.2rem;
    margin-bottom: 10px;
    line-height: 1.5;
}

.authors {
    color: #667eea;
    font-weight: 500;
    margin-bottom: 5px;
}

.venue {
    color: #666;
    font-size: 0.95rem;
    margin-bottom: 15px;
}

.paper-link {
    color: #667eea;
    text-decoration: none;
    font-weight: 500;
    border-bottom: 2px solid transparent;
    transition: border-color 0.3s ease;
}

.paper-link:hover {
    border-color: #667eea;
}

.contact {
    background: #fff;
}

.contact-info {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 40px;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 12px;
    color: #555;
    font-size: 1.1rem;
}

.contact-item i {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    font-size: 1rem;
}

.footer {
    background: #1a1a2e;
    color: #fff;
    text-align: center;
    padding: 30px;
}

.footer p {
    opacity: 0.7;
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 60px;
        left: 0;
        width: 100%;
        background: #1a1a2e;
        padding: 20px;
    }

    .nav-links li {
        margin: 10px 0;
    }

    .hamburger {
        display: flex;
    }

    .hero h1 {
        font-size: 2.2rem;
    }

    .hero h2 {
        font-size: 1.2rem;
    }

    .section-title {
        font-size: 1.8rem;
    }

    .contact-info {
        flex-direction: column;
        align-items: center;
    }
}

html {
    scroll-behavior: smooth;
}

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

.research-card, .timeline-item, .publication-item {
    animation: fadeInUp 0.6s ease-out;
}

.knowledge-hero {
    min-height: 40vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #11998e 0%, #38ef7d 100%);
    text-align: center;
    color: #fff;
    padding-top: 80px;
}

.knowledge-hero h1 {
    font-size: 2.8rem;
    margin-bottom: 15px;
}

.knowledge-hero p {
    font-size: 1.2rem;
    opacity: 0.9;
}

.knowledge-content {
    padding: 50px 0;
    background: #f8f9fa;
}

.filter-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 40px;
    flex-wrap: wrap;
    gap: 20px;
}

.search-box {
    flex: 1;
    min-width: 300px;
    max-width: 400px;
}

.search-input {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    font-size: 0.95rem;
    transition: border-color 0.3s ease;
}

.search-input:focus {
    outline: none;
    border-color: #11998e;
}

.category-filters {
    display: flex;
    gap: 10px;
}

.filter-btn {
    padding: 10px 25px;
    border: 2px solid #e2e8f0;
    background: #fff;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.95rem;
    transition: all 0.3s ease;
}

.filter-btn:hover,
.filter-btn.active {
    background: linear-gradient(135deg, #11998e 0%, #38ef7d 100%);
    color: #fff;
    border-color: transparent;
}

.knowledge-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 25px;
    max-width: 800px;
    margin: 0 auto;
}

.knowledge-card {
    background: #fff;
    border-radius: 12px;
    padding: 25px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.knowledge-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.category-badge {
    padding: 5px 14px;
    background: linear-gradient(135deg, #11998e 0%, #38ef7d 100%);
    color: #fff;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
}

.year,
.rating {
    color: #888;
    font-size: 0.9rem;
}

.rating {
    color: #f59e0b;
}

.knowledge-card.website .category-badge,
.knowledge-card.tool .category-badge {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.knowledge-card h3 {
    font-size: 1.2rem;
    color: #2d3748;
    margin-bottom: 10px;
    line-height: 1.4;
}

.knowledge-card .authors {
    color: #667eea;
    font-size: 0.9rem;
    margin-bottom: 10px;
    font-weight: 500;
}

.knowledge-card .summary {
    color: #555;
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: 15px;
}

.book-cover {
    width: 100%;
    height: 150px;
    background: linear-gradient(135deg, #e2e8f0 0%, #f1f5f9 100%);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 15px;
    font-size: 3rem;
    color: #94a3b8;
}

.knowledge-card .tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.knowledge-card .tags .tag {
    padding: 5px 12px;
    background: #f0f2f5;
    color: #666;
    border-radius: 15px;
    font-size: 0.8rem;
}

.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 10px;
    margin-top: 40px;
}

.page-btn {
    padding: 10px 18px;
    background: #fff;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    color: #555;
    cursor: pointer;
    font-size: 0.95rem;
    transition: all 0.3s ease;
}

.page-btn:hover,
.page-btn.active {
    background: linear-gradient(135deg, #11998e 0%, #38ef7d 100%);
    color: #fff;
    border-color: transparent;
}

.page-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

@media (max-width: 768px) {
    .filter-bar {
        flex-direction: column;
        align-items: stretch;
    }

    .search-box {
        max-width: 100%;
    }

    .category-filters {
        justify-content: center;
    }

    .knowledge-hero h1 {
        font-size: 2.2rem;
    }

    .knowledge-card h3 {
        font-size: 1.1rem;
    }
}