/* ===============================
   CSS Variables & Reset
   =============================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #1a1a2e;
    --secondary-color: #4f46e5;
    --accent-color: #06b6d4;
    --accent-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --text-color: #334155;
    --text-light: #64748b;
    --light-bg: #f8fafc;
    --white: #ffffff;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.12);
    --shadow: 0 10px 40px rgba(0,0,0,0.1);
    --shadow-lg: 0 25px 50px rgba(0,0,0,0.15);
    --gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-dark: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    --border-radius: 16px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ===============================
   Base Styles
   =============================== */
html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', 'Noto Sans SC', -apple-system, BlinkMacSystemFont, sans-serif;
    line-height: 1.7;
    color: var(--text-color);
    background: var(--white);
    overflow-x: hidden;
}

::selection {
    background: var(--secondary-color);
    color: white;
}

a {
    color: inherit;
    text-decoration: none;
    transition: var(--transition);
}

/* ===============================
   Navigation Bar
   =============================== */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    z-index: 1000;
    padding: 1rem 0;
    box-shadow: none;
    transition: var(--transition);
}

.navbar.scrolled {
    background: rgba(255, 255, 255, 0.98);
    box-shadow: var(--shadow-sm);
    padding: 0.75rem 0;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 2rem;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
}

.logo-text {
    font-size: 1.5rem;
    color: var(--primary-color);
}

.logo-divider {
    color: var(--text-light);
    font-weight: 300;
}

.logo-subtitle {
    font-size: 0.9rem;
    color: var(--secondary-color);
    font-weight: 500;
}

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

.nav-links a {
    color: var(--text-color);
    font-weight: 500;
    font-size: 0.95rem;
    position: relative;
    padding: 0.5rem 0;
}

.nav-links a:hover {
    color: var(--secondary-color);
}

.nav-links a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    background: var(--gradient);
    border-radius: 2px;
    transition: width 0.3s ease;
}

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

.nav-toggle {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--primary-color);
}

/* Mobile Menu */
.mobile-menu {
    display: none;
    position: fixed;
    top: 70px;
    left: 0;
    right: 0;
    background: white;
    padding: 1rem;
    box-shadow: var(--shadow);
    z-index: 999;
}

.mobile-menu.active {
    display: block;
}

.mobile-nav-links {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.mobile-nav-links a {
    display: block;
    padding: 0.75rem 1rem;
    color: var(--text-color);
    font-weight: 500;
    border-radius: 8px;
    transition: var(--transition);
}

.mobile-nav-links a:hover {
    background: var(--light-bg);
    color: var(--secondary-color);
}

/* ===============================
   Hero Section
   =============================== */
.hero {
    background: var(--gradient);
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
    padding-top: 80px;
}

.hero-particles {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 80%, rgba(255,255,255,0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(255,255,255,0.1) 0%, transparent 50%),
        url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1000 1000"><polygon fill="%23ffffff05" points="0,0 1000,300 1000,1000 0,700"/></svg>');
    background-size: cover;
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 4rem;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-text {
    color: white;
}

.greeting {
    font-size: 1.1rem;
    opacity: 0.9;
    margin-bottom: 0.5rem;
    opacity: 0;
    animation: slideInLeft 0.8s ease 0.3s forwards;
}

.hero-text h1 {
    font-size: 4rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    line-height: 1.1;
    opacity: 0;
    animation: slideInLeft 0.8s ease 0.5s forwards;
}

.hero-text h1 .name-en {
    display: block;
    font-size: 1.5rem;
    font-weight: 400;
    opacity: 0.8;
    margin-top: 0.25rem;
}

.hero-text .subtitle {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    opacity: 0.95;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    opacity: 0;
    animation: slideInLeft 0.8s ease 0.7s forwards;
}

.hero-text .subtitle i {
    font-size: 1rem;
}

.hero-text .description {
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
    opacity: 0.85;
    line-height: 1.8;
    max-width: 540px;
    opacity: 0;
    animation: slideInLeft 0.8s ease 0.9s forwards;
}

.description .highlight {
    color: #fbbf24;
    font-weight: 600;
}

.research-interests {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 2rem;
    opacity: 0;
    animation: slideInLeft 0.8s ease 1s forwards;
}

.interest-tag {
    background: rgba(255,255,255,0.15);
    backdrop-filter: blur(10px);
    padding: 0.5rem 1rem;
    border-radius: 50px;
    font-size: 0.85rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    border: 1px solid rgba(255,255,255,0.2);
    transition: var(--transition);
}

.interest-tag:hover {
    background: rgba(255,255,255,0.25);
    transform: translateY(-2px);
}

.cta-buttons {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
    margin-bottom: 2rem;
    opacity: 0;
    animation: slideInLeft 0.8s ease 1.1s forwards;
}

.btn {
    padding: 0.875rem 1.75rem;
    border: none;
    border-radius: 50px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

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

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 15px 35px rgba(0,0,0,0.2);
}

.btn-secondary {
    background: rgba(255,255,255,0.2);
    color: white;
    border: 1px solid rgba(255,255,255,0.3);
}

.btn-secondary:hover {
    background: rgba(255,255,255,0.3);
    transform: translateY(-3px);
}

.btn-outline {
    background: transparent;
    color: white;
    border: 2px solid rgba(255,255,255,0.5);
}

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

.social-links {
    display: flex;
    gap: 1rem;
    opacity: 0;
    animation: slideInLeft 0.8s ease 1.2s forwards;
}

.social-link {
    width: 45px;
    height: 45px;
    border-radius: 50%;
    background: rgba(255,255,255,0.1);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    color: white;
    border: 1px solid rgba(255,255,255,0.2);
    transition: var(--transition);
}

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

/* Hero Image */
.hero-image {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 0;
    animation: slideInRight 0.8s ease 0.5s forwards;
}

.profile-wrapper {
    position: relative;
}

.profile-ring {
    position: absolute;
    top: -15px;
    left: -15px;
    right: -15px;
    bottom: -15px;
    border: 3px solid rgba(255,255,255,0.2);
    border-radius: 50%;
    animation: pulse 3s ease-in-out infinite;
}

.profile-img {
    width: 320px;
    height: 320px;
    border-radius: 50%;
    object-fit: cover;
    border: 6px solid rgba(255,255,255,0.3);
    box-shadow: 0 25px 60px rgba(0,0,0,0.3);
    transition: var(--transition);
}

.profile-img:hover {
    transform: scale(1.03);
    border-color: rgba(255,255,255,0.5);
}

.profile-badge {
    position: absolute;
    bottom: 20px;
    right: 20px;
    width: 60px;
    height: 60px;
    background: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--secondary-color);
    font-size: 1.5rem;
    box-shadow: var(--shadow);
}

.floating-cards {
    position: absolute;
    width: 100%;
    height: 100%;
    pointer-events: none;
}

.float-card {
    position: absolute;
    background: white;
    padding: 0.75rem 1.25rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--primary-color);
}

.float-card i {
    color: var(--secondary-color);
}

.card-1 {
    top: 20%;
    left: -30px;
    animation: float 3s ease-in-out infinite;
}

.card-2 {
    bottom: 20%;
    right: -30px;
    animation: float 3s ease-in-out infinite 1.5s;
}

.scroll-indicator {
    position: absolute;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 10;
}

.scroll-indicator a {
    display: flex;
    flex-direction: column;
    align-items: center;
    color: white;
    opacity: 0.7;
    animation: bounce 2s infinite;
}

.scroll-indicator i {
    font-size: 1.5rem;
}

/* ===============================
   Content Sections
   =============================== */
.section {
    padding: 6rem 0;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3.5rem;
    color: var(--primary-color);
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
}

.title-icon {
    width: 50px;
    height: 50px;
    background: var(--gradient);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.25rem;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -15px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: var(--gradient);
    border-radius: 2px;
}

/* ===============================
   About Section
   =============================== */
.about {
    background: var(--white);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 4rem;
    align-items: start;
}

.about-stats {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
}

.stat-card {
    background: var(--white);
    padding: 2rem 1.5rem;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.stat-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--gradient);
}

.stat-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.stat-icon {
    width: 50px;
    height: 50px;
    background: var(--light-bg);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1rem;
    color: var(--secondary-color);
    font-size: 1.25rem;
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--secondary-color);
    margin-bottom: 0.25rem;
    display: inline-block;
}

.stat-suffix {
    font-size: 1.5rem;
    color: var(--secondary-color);
}

.stat-label {
    color: var(--text-light);
    font-weight: 500;
    font-size: 0.9rem;
}

.about-text {
    font-size: 1.05rem;
    line-height: 1.9;
    color: var(--text-color);
}

.about-intro {
    margin-bottom: 1.5rem;
}

.about-intro .lead {
    font-size: 1.2rem;
    color: var(--primary-color);
    position: relative;
    padding-left: 1.5rem;
}

.quote-icon {
    position: absolute;
    left: 0;
    top: 0;
    color: var(--secondary-color);
    font-size: 1rem;
    opacity: 0.5;
}

.about-details p {
    margin-bottom: 1rem;
}

.about-details strong {
    color: var(--secondary-color);
}

.skills-section {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid #e2e8f0;
}

.skills-section h4 {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    color: var(--primary-color);
}

.skills-section h4 i {
    color: var(--secondary-color);
}

.skills-grid {
    display: grid;
    gap: 1rem;
}

.skill-item {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.skill-name {
    min-width: 140px;
    font-weight: 500;
    color: var(--text-color);
}

.skill-bar {
    flex: 1;
    height: 8px;
    background: var(--light-bg);
    border-radius: 4px;
    overflow: hidden;
}

.skill-progress {
    height: 100%;
    background: var(--gradient);
    border-radius: 4px;
    transition: width 1s ease;
}

/* ===============================
   Education Section
   =============================== */
.education {
    background: var(--light-bg);
}

.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
    padding-left: 40px;
}

.timeline-line {
    position: absolute;
    top: 0;
    left: 20px;
    width: 3px;
    height: 100%;
    background: linear-gradient(to bottom, var(--secondary-color), var(--accent-color));
    border-radius: 3px;
}

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
    padding-left: 40px;
}

.timeline-item:last-child {
    margin-bottom: 0;
}

.timeline-dot {
    position: absolute;
    left: -30px;
    top: 0;
    width: 50px;
    height: 50px;
    background: var(--gradient);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.1rem;
    box-shadow: 0 0 0 6px var(--light-bg), var(--shadow);
    z-index: 1;
}

.timeline-content {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.timeline-content:hover {
    transform: translateX(10px);
    box-shadow: var(--shadow-lg);
}

.timeline-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.75rem;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.timeline-year {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--secondary-color);
    font-weight: 600;
    font-size: 0.95rem;
}

.timeline-status {
    padding: 0.25rem 0.75rem;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 600;
}

.status-current {
    background: #dcfce7;
    color: #16a34a;
}

.status-completed {
    background: #e0e7ff;
    color: var(--secondary-color);
}

.timeline-title {
    font-size: 1.4rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.timeline-institution {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-light);
    font-weight: 500;
    margin-bottom: 1rem;
}

.timeline-institution i {
    color: var(--secondary-color);
}

.timeline-description {
    color: var(--text-color);
    line-height: 1.7;
}

.timeline-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1rem;
}

.timeline-tag {
    background: var(--light-bg);
    color: var(--secondary-color);
    padding: 0.25rem 0.75rem;
    border-radius: 50px;
    font-size: 0.8rem;
    font-weight: 500;
}

.timeline-achievements {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
}

.achievement {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: #fef3c7;
    color: #d97706;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.9rem;
}

.achievement i {
    color: #f59e0b;
}

/* ===============================
   Research Section
   =============================== */
.research {
    background: var(--white);
}

.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
    gap: 2rem;
}

.research-card {
    background: var(--white);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 1px solid #e2e8f0;
    position: relative;
    overflow: hidden;
}

.research-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--gradient);
}

.research-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: transparent;
}

.research-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.research-icon {
    width: 60px;
    height: 60px;
    background: var(--gradient);
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    color: white;
    flex-shrink: 0;
}

.research-icon.icon-purple {
    background: linear-gradient(135deg, #8b5cf6 0%, #a855f7 100%);
}

.research-icon.icon-green {
    background: linear-gradient(135deg, #10b981 0%, #14b8a6 100%);
}

.research-category {
    color: var(--secondary-color);
    font-weight: 600;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.research-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--primary-color);
    line-height: 1.4;
}

.research-description {
    color: var(--text-color);
    line-height: 1.7;
    margin-bottom: 1.5rem;
}

.research-description p {
    margin-bottom: 1rem;
}

.research-highlights {
    list-style: none;
    margin-top: 1rem;
}

.research-highlights li {
    display: flex;
    align-items: flex-start;
    gap: 0.5rem;
    margin-bottom: 0.5rem;
    font-size: 0.95rem;
    color: var(--text-color);
}

.research-highlights li i {
    color: #10b981;
    margin-top: 0.25rem;
}

.research-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

.tag {
    background: var(--light-bg);
    color: var(--text-color);
    padding: 0.4rem 0.9rem;
    border-radius: 50px;
    font-size: 0.8rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 0.4rem;
    transition: var(--transition);
}

.tag i {
    font-size: 0.75rem;
    color: var(--secondary-color);
}

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

.tag:hover i {
    color: white;
}

.research-footer {
    padding-top: 1rem;
    border-top: 1px solid #e2e8f0;
}

.venue {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--accent-color);
    font-weight: 600;
    font-size: 0.9rem;
}

.venue i {
    color: var(--secondary-color);
}

/* ===============================
   Publications Section
   =============================== */
.publications {
    background: var(--light-bg);
}

.publication-filters {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 0.6rem 1.5rem;
    border: 2px solid #e2e8f0;
    background: white;
    border-radius: 50px;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    color: var(--text-color);
}

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

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

.publication-item {
    background: var(--white);
    padding: 2rem;
    margin-bottom: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
    display: flex;
    gap: 2rem;
    position: relative;
    overflow: hidden;
}

.publication-item::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 4px;
    background: var(--gradient);
}

.publication-item:hover {
    transform: translateX(10px);
    box-shadow: var(--shadow-lg);
}

.publication-number {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--light-bg);
    line-height: 1;
    min-width: 60px;
}

.publication-content {
    flex: 1;
}

.publication-venue-badge {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 0.75rem;
}

.badge-ccf {
    background: linear-gradient(135deg, #ef4444 0%, #f97316 100%);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 700;
}

.badge-year {
    background: var(--secondary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 600;
}

.publication-title {
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    color: var(--primary-color);
    line-height: 1.5;
}

.title-cn {
    display: block;
    font-size: 0.95rem;
    color: var(--text-light);
    font-weight: 500;
    margin-top: 0.25rem;
}

.publication-authors {
    color: var(--text-color);
    margin-bottom: 0.5rem;
    font-size: 0.95rem;
    line-height: 1.6;
}

.author {
    display: inline;
}

.highlight-author {
    font-weight: 700;
    color: var(--secondary-color);
}

.publication-journal {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-light);
    font-weight: 500;
    margin-bottom: 1rem;
}

.publication-journal i {
    color: var(--secondary-color);
}

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

.pub-link {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    color: var(--secondary-color);
    font-size: 0.9rem;
    font-weight: 500;
    padding: 0.4rem 0.8rem;
    background: var(--light-bg);
    border-radius: 6px;
    transition: var(--transition);
}

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

/* ===============================
   Contact Section
   =============================== */
.contact {
    background: var(--gradient-dark);
    color: white;
    position: relative;
    overflow: hidden;
}

.contact::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1000 1000"><circle fill="%23ffffff05" cx="100" cy="100" r="200"/><circle fill="%23ffffff05" cx="900" cy="800" r="300"/></svg>');
}

.contact .container {
    position: relative;
    z-index: 1;
}

.contact .section-title::after {
    background: white;
}

.contact-intro {
    text-align: center;
    margin-bottom: 3rem;
    opacity: 0.9;
    font-size: 1.1rem;
}

.contact-content-simple {
    max-width: 900px;
    margin: 0 auto;
}

.contact-info-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    background: rgba(255,255,255,0.08);
    padding: 1.5rem 2rem;
    border-radius: var(--border-radius);
    backdrop-filter: blur(10px);
    transition: var(--transition);
    border: 1px solid rgba(255,255,255,0.1);
}

.contact-item:hover {
    transform: translateY(-5px);
    background: rgba(255,255,255,0.12);
    border-color: rgba(255,255,255,0.2);
}

.contact-icon {
    width: 55px;
    height: 55px;
    background: var(--secondary-color);
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.3rem;
    color: white;
    flex-shrink: 0;
}

.contact-details {
    flex: 1;
}

.contact-label {
    font-weight: 600;
    margin-bottom: 0.25rem;
    color: rgba(255,255,255,0.7);
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.contact-value {
    font-size: 1rem;
    color: white;
    line-height: 1.5;
}

.contact-value a {
    color: white;
    text-decoration: underline;
    text-underline-offset: 3px;
}

.contact-value a:hover {
    color: var(--accent-color);
}

/* ===============================
   Footer
   =============================== */
.footer {
    background: #0f0f1a;
    color: white;
    padding: 4rem 0 2rem;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 2rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid rgba(255,255,255,0.1);
}

.footer-logo {
    display: flex;
    flex-direction: column;
}

.footer-logo .logo-text {
    font-size: 1.5rem;
    font-weight: 700;
}

.footer-logo .logo-subtitle {
    color: var(--text-light);
    font-size: 0.9rem;
}

.footer-links {
    display: flex;
    gap: 2rem;
    flex-wrap: wrap;
}

.footer-links a {
    color: rgba(255,255,255,0.7);
    font-size: 0.95rem;
    transition: var(--transition);
}

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

.footer-social {
    display: flex;
    gap: 1rem;
}

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

.footer-social a:hover {
    background: var(--secondary-color);
    transform: translateY(-3px);
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    color: rgba(255,255,255,0.5);
    font-size: 0.9rem;
}

.footer-bottom p {
    margin-bottom: 0.25rem;
}

/* ===============================
   Back to Top Button
   =============================== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--gradient);
    border: none;
    border-radius: 50%;
    color: white;
    font-size: 1.25rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    box-shadow: var(--shadow);
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

/* ===============================
   Animations
   =============================== */
@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-50px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(50px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

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

@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-15px);
    }
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
        opacity: 0.5;
    }
    50% {
        transform: scale(1.05);
        opacity: 0.8;
    }
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateY(0);
    }
    40% {
        transform: translateY(-10px);
    }
    60% {
        transform: translateY(-5px);
    }
}

/* ===============================
   Scroll Animations
   =============================== */
.scroll-animation {
    opacity: 0;
    transform: translateY(40px);
    transition: all 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

.scroll-animation.animate {
    opacity: 1;
    transform: translateY(0);
}

/* ===============================
   Responsive Design
   =============================== */
@media (max-width: 1024px) {
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 3rem;
    }
    
    .hero-text .description {
        max-width: 100%;
    }
    
    .cta-buttons {
        justify-content: center;
    }
    
    .social-links {
        justify-content: center;
    }
    
    .research-interests {
        justify-content: center;
    }
    
    .about-content {
        grid-template-columns: 1fr;
        gap: 3rem;
    }
    
    .contact-info-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .nav-toggle {
        display: block;
    }
    
    .hero {
        padding-top: 100px;
    }
    
    .hero-text h1 {
        font-size: 2.75rem;
    }
    
    .hero-text .subtitle {
        font-size: 1.1rem;
        flex-direction: column;
        gap: 0.5rem;
    }
    
    .profile-img {
        width: 250px;
        height: 250px;
    }
    
    .floating-cards {
        display: none;
    }
    
    .section {
        padding: 4rem 0;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .about-stats {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .timeline {
        padding-left: 30px;
    }
    
    .timeline-line {
        left: 10px;
    }
    
    .timeline-item {
        padding-left: 30px;
    }
    
    .timeline-dot {
        left: -20px;
        width: 40px;
        height: 40px;
        font-size: 0.9rem;
    }
    
    .research-grid {
        grid-template-columns: 1fr;
    }
    
    .publication-item {
        flex-direction: column;
        gap: 1rem;
    }
    
    .publication-number {
        font-size: 1.5rem;
    }
    
    .cta-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        width: 100%;
        max-width: 280px;
        justify-content: center;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
    }
    
    .footer-links {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .hero-text h1 {
        font-size: 2.25rem;
    }
    
    .profile-img {
        width: 200px;
        height: 200px;
    }
    
    .about-stats {
        grid-template-columns: 1fr;
    }
    
    .stat-card {
        padding: 1.5rem;
    }
    
    .timeline-content {
        padding: 1.5rem;
    }
    
    .research-card {
        padding: 1.5rem;
    }
    
    .publication-item {
        padding: 1.5rem;
    }
}