:root {
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --info-color: #06b6d4;
    --dark-color: #1f2937;
    --light-color: #f9fafb;
}

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

body {
    font-family: 'Inter', sans-serif;
    overflow-x: hidden;
    color: #1f2937;
}

/* Navigation */
#mainNav {
    background: rgba(26, 32, 44, 0.95);
    backdrop-filter: blur(10px);
    transition: all 0.3s ease;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

#mainNav.navbar-scrolled {
    background: rgba(26, 32, 44, 1);
}

.navbar-brand {
    font-size: 1.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-link {
    position: relative;
    padding: 0.5rem 1rem !important;
    transition: all 0.3s ease;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 2px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    transition: width 0.3s ease;
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 80%;
}

/* Hero Section */
.hero-section {
    min-height: 100vh;
    position: relative;
    padding: 100px 0;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    z-index: -1;
}

.hero-background::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        radial-gradient(circle at 20% 50%, rgba(255, 255, 255, 0.1) 1px, transparent 1px),
        radial-gradient(circle at 80% 80%, rgba(255, 255, 255, 0.1) 1px, transparent 1px);
    background-size: 50px 50px;
    animation: backgroundMove 20s linear infinite;
}

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

.profile-card {
    animation: float 6s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-20px); }
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
}

.scroll-indicator {
    position: absolute;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%);
}

.animate-bounce {
    animation: bounce 2s infinite;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

/* Section Divider */
.section-divider {
    width: 80px;
    height: 4px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 2px;
}

/* Timeline */
.timeline-item {
    position: relative;
}

.timeline-marker {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    flex-shrink: 0;
    margin-top: 5px;
}

.timeline-content h6 {
    font-weight: 600;
    color: #1f2937;
}

/* Research Cards */
.research-card {
    background: white;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.research-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 40px rgba(0,0,0,0.15) !important;
    border-color: var(--primary-color);
}

.research-icon {
    transition: transform 0.3s ease;
}

.research-card:hover .research-icon {
    transform: scale(1.2) rotate(5deg);
}

/* Publications */
.publication-card {
    border-left: 4px solid var(--primary-color);
    transition: all 0.3s ease;
}

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

.publication-year {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 0.25rem 1rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
}

.journal-name {
    color: var(--info-color);
    font-weight: 600;
}

/* Filter Buttons */
.filter-btn {
    border: 2px solid #e5e7eb;
    background: white;
    color: #6b7280;
    padding: 0.5rem 1.5rem;
    border-radius: 25px;
    transition: all 0.3s ease;
    font-weight: 500;
}

.filter-btn:hover,
.filter-btn.active {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border-color: transparent;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.3);
}

/* Experience Timeline */
.experience-timeline {
    position: relative;
    padding-left: 40px;
}

.experience-timeline::before {
    content: '';
    position: absolute;
    left: 15px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: linear-gradient(to bottom, var(--primary-color), var(--secondary-color));
}

.experience-item {
    position: relative;
    margin-bottom: 2rem;
}

.experience-item::before {
    content: '';
    position: absolute;
    left: -32px;
    top: 8px;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: white;
    border: 3px solid var(--primary-color);
    box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.1);
}

.experience-card {
    background: white;
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
    transition: all 0.3s ease;
}

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

.experience-badge {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.75rem;
    font-weight: 600;
}

/* Awards */
.award-card {
    background: white;
    border-radius: 12px;
    padding: 1.5rem;
    border-left: 4px solid var(--warning-color);
    transition: all 0.3s ease;
}

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

.award-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--warning-color), #ef4444);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.5rem;
}

/* Gallery */
.gallery-item {
    position: relative;
    overflow: hidden;
    border-radius: 12px;
    cursor: pointer;
    height: 300px;
}

.gallery-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.5s ease;
}

.gallery-item:hover img {
    transform: scale(1.1);
}

.gallery-overlay {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: linear-gradient(to top, rgba(0,0,0,0.8), transparent);
    padding: 1.5rem;
    transform: translateY(100%);
    transition: transform 0.3s ease;
}

.gallery-item:hover .gallery-overlay {
    transform: translateY(0);
}

.gallery-category {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.75rem;
    margin-bottom: 0.5rem;
}

/* Contact Form */
.contact-info-box {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
    height: 100%;
    border-left: 4px solid var(--primary-color);
}

.contact-icon {
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.25rem;
    margin-bottom: 1rem;
}

.form-control:focus,
.form-select:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.2rem rgba(102, 126, 234, 0.25);
}

/* Back to Top Button */
#backToTop {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    z-index: 1000;
    display: none;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border: none;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
    transition: all 0.3s ease;
}

#backToTop:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.5);
}

/* Utilities */
.hover-link:hover {
    color: var(--primary-color) !important;
    padding-left: 5px;
    transition: all 0.3s ease;
}

.gradient-text {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Responsive */
@media (max-width: 768px) {
    .hero-section {
        min-height: auto;
        padding: 80px 0 40px;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .experience-timeline {
        padding-left: 20px;
    }
    
    .experience-timeline::before {
        left: 0;
    }
    
    .experience-item::before {
        left: -14px;
    }
}

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

.fade-in {
    animation: fadeIn 0.6s ease-out;
}

/* Page Header */
.page-header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 120px 0 80px;
    color: white;
    position: relative;
    overflow: hidden;
}

.page-header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        radial-gradient(circle at 20% 50%, rgba(255, 255, 255, 0.1) 1px, transparent 1px),
        radial-gradient(circle at 80% 80%, rgba(255, 255, 255, 0.1) 1px, transparent 1px);
    background-size: 50px 50px;
}

/* Search Bar */
.search-bar {
    max-width: 500px;
    margin: 0 auto;
}

.search-bar input {
    border-radius: 25px;
    padding: 0.75rem 1.5rem;
    border: 2px solid #e5e7eb;
}

.search-bar input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.2rem rgba(102, 126, 234, 0.25);
}