:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --border-color: #e5e7eb;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    overflow-x: hidden;
}

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

/* Navbar */
.navbar {
    background-color: var(--bg-primary);
    box-shadow: var(--shadow);
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    transition: all 0.3s ease;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

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

.nav-link {
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-link:hover {
    color: var(--primary-color);
}

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

.bar {
    width: 25px;
    height: 3px;
    background-color: var(--text-primary);
    margin: 3px 0;
    transition: 0.3s;
}

/* Hero Section */
.hero {
    margin-top: 80px;
    padding: 80px 0;
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
}

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

.profile-section {
    display: flex;
    align-items: center;
    gap: 60px;
    flex-wrap: wrap;
    justify-content: center;
}

.profile-image-container {
    position: relative;
}

.profile-image {
    width: 250px;
    height: 250px;
    border-radius: 50%;
    object-fit: cover;
    box-shadow: var(--shadow-lg);
    border: 5px solid var(--bg-primary);
}

.profile-info {
    text-align: center;
    flex: 1;
    min-width: 300px;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.hero-university {
    font-size: 1.25rem;
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 2rem;
}

.social-links {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
}

.social-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 45px;
    height: 45px;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    border-radius: 50%;
    text-decoration: none;
    transition: all 0.3s ease;
    font-size: 1.2rem;
}

.social-link:hover {
    background-color: var(--primary-color);
    color: white;
    transform: translateY(-3px);
}

/* About Section */
.about {
    padding: 80px 0;
    background-color: var(--bg-primary);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.about-content p {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.8;
}

/* Publications Section */
.publications {
    padding: 80px 0;
    background-color: var(--bg-secondary);
}

.publication-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.publication-card {
    background-color: var(--bg-primary);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.publication-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.publication-year {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background-color: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
}

.publication-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.75rem;
    margin-right: 60px;
    transition: color 0.3s ease;
}

.publication-title-link .publication-title {
    color: #1e40af;
}

.publication-title-link:hover .publication-title {
    color: var(--primary-color);
    text-decoration: underline;
}

.publication-authors {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.publication-venue {
    font-size: 0.95rem;
    color: var(--primary-color);
    font-style: italic;
    margin-bottom: 1.5rem;
}

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

.pub-link {
    padding: 0.5rem 1rem;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    text-decoration: none;
    border-radius: 6px;
    font-size: 0.875rem;
    font-weight: 500;
    transition: all 0.3s ease;
}

.pub-link:hover {
    background-color: var(--primary-color);
    color: white;
}

/* Contact Section */
.contact {
    padding: 80px 0;
    background-color: var(--bg-primary);
}

.contact-content {
    text-align: center;
}

.contact-content p {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.contact-email {
    font-size: 1.5rem;
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.3s ease;
}

.contact-email:hover {
    color: var(--secondary-color);
}

/* Footer */
.footer {
    background-color: var(--text-primary);
    color: white;
    padding: 2rem 0;
    text-align: center;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }

    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: var(--bg-primary);
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--shadow);
        padding: 2rem 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-item {
        margin: 1rem 0;
    }

    .hero-title {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1.125rem;
    }

    .profile-section {
        flex-direction: column;
        text-align: center;
    }

    .profile-image {
        width: 200px;
        height: 200px;
    }

    .publication-grid {
        grid-template-columns: 1fr;
    }
}

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

.publication-card {
    animation: fadeIn 0.5s ease-out;
}

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

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--primary-color);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--secondary-color);
}

/* Research Interests */
.research-interests {
    margin-top: 3rem;
    text-align: center;
}

.research-interests h3 {
    font-size: 1.5rem;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
}

.interest-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: center;
}

.interest-tag {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    border-radius: 30px;
    font-weight: 500;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.interest-tag:hover {
    background-color: var(--primary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.interest-tag i {
    font-size: 1.1rem;
}

/* Filter Buttons */
.filter-container {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 3rem;
}

.filter-btn {
    padding: 0.75rem 1.5rem;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    border: 2px solid transparent;
    border-radius: 30px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.filter-btn:hover {
    background-color: var(--primary-color);
    color: white;
}

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

/* Year Dividers */
.year-divider {
    position: relative;
    width: 100%;
    margin: 2rem 0;
    display: flex;
    align-items: center;
    justify-content: flex-end;
    grid-column: 1 / -1;  /* Span all columns in grid */
}

.year-line {
    position: absolute;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(to right, transparent, #d1d5db 10%, #d1d5db 90%, transparent);
    opacity: 0.7;
}

.year-label {
    position: relative;
    background-color: var(--bg-primary);
    padding: 0 1rem;
    color: #9ca3af;
    font-size: 0.875rem;
    font-weight: 500;
    letter-spacing: 0.05em;
}

/* Category Badges */
.category-badges {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.category-badge {
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
}

.category-badge.multimodal {
    background-color: #ddd6fe;
    color: #6b21a8;
}

.category-badge.speech {
    background-color: #fed7aa;
    color: #c2410c;
}

.category-badge.reasoning {
    background-color: #bfdbfe;
    color: #1e40af;
}

.category-badge.realtime {
    background-color: #d1fae5;
    color: #047857;
}

.category-badge.etc {
    background-color: #e5e7eb;
    color: #374151;
}

/* Highlighted Publications */
.publication-card.highlight {
    border: 2px solid var(--primary-color);
    background: linear-gradient(135deg, var(--bg-primary) 0%, #f0f9ff 100%);
}

/* Publication Abstract */
.publication-abstract {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    line-height: 1.6;
}

/* No Papers Message */
.no-papers {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.125rem;
    padding: 3rem;
}

/* BibTeX Modal */
.bibtex-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    animation: fadeIn 0.3s ease;
}

.bibtex-content {
    background-color: var(--bg-primary);
    padding: 2rem;
    border-radius: 12px;
    max-width: 600px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
    box-shadow: var(--shadow-lg);
}

.bibtex-content h3 {
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.bibtex-content pre {
    background-color: var(--bg-secondary);
    padding: 1rem;
    border-radius: 6px;
    overflow-x: auto;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    line-height: 1.4;
    margin-bottom: 1.5rem;
}

.copy-btn, .close-btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-right: 1rem;
}

.copy-btn {
    background-color: var(--primary-color);
    color: white;
}

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

.close-btn {
    background-color: var(--bg-secondary);
    color: var(--text-primary);
}

.close-btn:hover {
    background-color: var(--border-color);
}

/* Enhanced Link Styles */
.pub-link {
    display: inline-flex;
    align-items: center;
    gap: 0.3rem;
}

.pub-link i {
    font-size: 0.9rem;
}

.bibtex-btn {
    background-color: var(--bg-secondary);
    border: none;
    cursor: pointer;
    font-family: inherit;
}

.bibtex-btn:hover {
    background-color: var(--primary-color);
    color: white;
}

/* Publication Images */
.publication-image {
    width: 100%;
    margin-bottom: 1rem;
    border-radius: 8px;
    overflow: hidden;
    background-color: var(--bg-secondary);
}

.publication-image img {
    width: 100%;
    height: auto;
    display: block;
    object-fit: cover;
    max-height: 250px;
}

/* Responsive adjustments for publication cards with images */
@media (min-width: 768px) {
    .publication-grid {
        grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    }
}

/* Publication Title Link */
.publication-title-link {
    text-decoration: none;
    color: inherit;
    display: block;
}