/* ===========================
   Global Styles & Reset
   =========================== */

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

:root {
    /* Colors */
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --secondary-color: #8b5cf6;
    --accent-color: #ec4899;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --border-color: #e5e7eb;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    
    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'SF Mono', Monaco, Consolas, 'Liberation Mono', 'Courier New', monospace;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ===========================
   Navigation
   =========================== */

.navbar {
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    border-bottom: 1px solid var(--border-color);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: var(--spacing-lg);
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
    position: relative;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--primary-color);
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: width 0.3s ease;
}

.nav-links a:hover::after,
.nav-links a.active::after {
    width: 100%;
}

/* ===========================
   Hero Section
   =========================== */

.hero {
    min-height: 70vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    background: linear-gradient(135deg, 
        #667eea 0%, 
        #764ba2 25%, 
        #f093fb 50%, 
        #4facfe 75%, 
        #00f2fe 100%);
    background-size: 400% 400%;
    animation: gradient 15s ease infinite;
    padding: var(--spacing-2xl) 0;
}

@keyframes gradient {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 20% 50%, rgba(255, 255, 255, 0.1) 0%, transparent 50%),
                radial-gradient(circle at 80% 80%, rgba(255, 255, 255, 0.1) 0%, transparent 50%);
    animation: aurora 8s ease infinite;
}

@keyframes aurora {
    0%, 100% { opacity: 1; transform: translateY(0); }
    50% { opacity: 0.8; transform: translateY(-20px); }
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    color: white;
    max-width: 800px;
    padding: 0 var(--spacing-md);
    animation: fadeInUp 1s ease;
}

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

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: var(--spacing-sm);
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-md);
    opacity: 0.95;
    font-weight: 300;
}

.hero-description {
    font-size: 1.1rem;
    margin-bottom: var(--spacing-xl);
    opacity: 0.9;
    font-weight: 300;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
}

/* ===========================
   Buttons
   =========================== */

.btn {
    display: inline-block;
    padding: 0.875rem 2rem;
    border-radius: 0.5rem;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
    font-size: 1rem;
}

.btn-primary {
    background: white;
    color: var(--primary-color);
    box-shadow: var(--shadow-lg);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

.btn-secondary {
    background: transparent;
    color: white;
    border: 2px solid white;
}

.btn-secondary:hover {
    background: white;
    color: var(--primary-color);
    transform: translateY(-2px);
}

/* ===========================
   Info Strip
   =========================== */

.info-strip {
    background: var(--bg-secondary);
    padding: var(--spacing-xl) 0;
    border-bottom: 1px solid var(--border-color);
}

.info-strip .container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.info-item {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: white;
    border-radius: 0.75rem;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

.info-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.info-icon {
    font-size: 2rem;
    flex-shrink: 0;
}

.info-content h3 {
    font-size: 1.1rem;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.info-content p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* ===========================
   Featured Sections
   =========================== */

.featured-section {
    padding: var(--spacing-2xl) 0;
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-xl);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-cta {
    text-align: center;
    margin-top: var(--spacing-xl);
}

/* ===========================
   Publications
   =========================== */

.page-header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: var(--spacing-2xl) 0;
    text-align: center;
}

.page-header h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
}

.page-header p {
    font-size: 1.2rem;
    opacity: 0.9;
}

.filters-section {
    background: var(--bg-secondary);
    padding: var(--spacing-lg) 0;
    border-bottom: 1px solid var(--border-color);
}

.filters {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
    margin-bottom: var(--spacing-md);
}

.filter-group {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.filter-group label {
    font-weight: 600;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.filter-group input,
.filter-group select {
    padding: 0.5rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 0.95rem;
    min-width: 200px;
    transition: all 0.3s ease;
}

.filter-group input:focus,
.filter-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.results-count {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.publications-section {
    padding: var(--spacing-xl) 0;
}

.publications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.publications-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.publications-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

/* Publication group styles */
.publication-group {
    margin-bottom: var(--spacing-2xl);
}

.group-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-sm);
    border-bottom: 3px solid var(--primary-color);
}

.publication-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 0.75rem;
    padding: var(--spacing-lg);
    transition: all 0.3s ease;
    animation: fadeIn 0.5s ease;
}

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

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

.publication-type {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-sm);
}

.publication-type.journal {
    background: rgba(99, 102, 241, 0.1);
    color: var(--primary-color);
}

.publication-type.conference {
    background: rgba(139, 92, 246, 0.1);
    color: var(--secondary-color);
}

.publication-type.preprint {
    background: rgba(236, 72, 153, 0.1);
    color: var(--accent-color);
}

.publication-type.thesis {
    background: rgba(16, 185, 129, 0.1);
    color: #059669;
}

.publication-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    line-height: 1.4;
}

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

.publication-venue {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-style: italic;
    margin-bottom: var(--spacing-sm);
}

.publication-abstract {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
    margin-top: var(--spacing-sm);
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--border-color);
}

.publication-links {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
    flex-wrap: wrap;
}

.publication-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    color: var(--primary-color);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 600;
    transition: all 0.3s ease;
}

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

/* ===========================
   Projects
   =========================== */

.projects-section {
    padding: var(--spacing-xl) 0;
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-lg);
}

.project-card {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 0.75rem;
    padding: var(--spacing-lg);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
    animation: fadeIn 0.5s ease;
}

.project-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.3s ease;
}

.project-card:hover::before {
    transform: scaleX(1);
}

.project-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.project-name {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.project-description {
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.6;
    margin-bottom: var(--spacing-md);
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-md);
}

.project-tag {
    padding: 0.25rem 0.75rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 1rem;
    font-size: 0.8rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.project-tech {
    margin-bottom: var(--spacing-md);
}

.project-tech h4 {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
    font-weight: 600;
}

.project-tech-list {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.project-highlights {
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 0.5rem;
    margin-bottom: var(--spacing-md);
}

.project-highlights h4 {
    font-size: 0.9rem;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
    font-weight: 600;
}

.project-highlights ul {
    list-style-position: inside;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.project-links {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.project-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    color: var(--primary-color);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 600;
    transition: all 0.3s ease;
}

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

/* ===========================
   Footer
   =========================== */

.footer {
    background: var(--text-primary);
    color: white;
    padding: var(--spacing-2xl) 0 var(--spacing-lg);
    margin-top: var(--spacing-2xl);
}

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

.footer-section h3 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-md);
    color: white;
}

.footer-section p {
    color: rgba(255, 255, 255, 0.7);
    line-height: 1.6;
}

.social-links {
    display: flex;
    gap: var(--spacing-md);
}

.social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.1);
    color: white;
    transition: all 0.3s ease;
}

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

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

.footer-links li {
    margin-bottom: var(--spacing-xs);
}

.footer-links a {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    transition: color 0.3s ease;
}

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

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-bottom p {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.9rem;
}

/* ===========================
   Responsive Design
   =========================== */

@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.2rem;
    }
    
    .hero-description {
        font-size: 1rem;
    }
    
    .nav-links {
        gap: var(--spacing-md);
    }
    
    .filters {
        flex-direction: column;
    }
    
    .filter-group {
        width: 100%;
    }
    
    .filter-group input,
    .filter-group select {
        width: 100%;
    }
    
    .publications-grid,
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .page-header h1 {
        font-size: 2rem;
    }
}

/* ===========================
   Accessibility
   =========================== */

:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

/* ===========================
   Utility Classes
   =========================== */

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

.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }

.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }