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

:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --accent-color: #3b82f6;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --bg-light: #f8fafc;
    --bg-white: #ffffff;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-light);
}

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

/* Header */
header {
    background: var(--gradient);
    color: white;
    padding: 2rem 0;
    text-align: center;
    position: relative;
    overflow: hidden;
}

header::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 0 100 100"><defs><pattern id="grid" width="10" height="10" patternUnits="userSpaceOnUse"><path d="M 10 0 L 0 0 0 10" fill="none" stroke="white" stroke-width="0.5" opacity="0.1"/></pattern></defs><rect width="100" height="100" fill="url(%23grid)"/></svg>');
    opacity: 0.3;
}

.hero-content {
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    animation: fadeInUp 1s ease;
}

.hero-subtitle {
    font-size: 1.2rem;
    opacity: 0.9;
    margin-bottom: 1rem;
    animation: fadeInUp 1s ease 0.2s both;
}

.hero-description {
    font-size: 1rem;
    max-width: 600px;
    margin: 0 auto 2rem;
    opacity: 0.8;
    animation: fadeInUp 1s ease 0.4s both;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
    animation: fadeInUp 1s ease 0.6s both;
}

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

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    display: block;
}

.stat-label {
    font-size: 0.9rem;
    opacity: 0.8;
}

/* Navigation */
nav {
    background: var(--bg-white);
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    display: flex;
    justify-content: center;
    padding: 1rem 0;
}

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

.nav-links a {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    transition: all 0.3s ease;
}

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

/* Main Content */
main {
    padding: 4rem 0;
}

.section {
    margin-bottom: 6rem;
}

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

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: var(--primary-color);
    border-radius: 2px;
}

/* Skills Section */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.skill-category {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.08);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.skill-category:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 30px rgba(0,0,0,0.12);
}

.skill-category h3 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.skill-tag {
    background: var(--bg-light);
    color: var(--text-secondary);
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.85rem;
    border: 1px solid var(--border-color);
}

/* Projects Section */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

.project-card {
    background: var(--bg-white);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 20px rgba(0,0,0,0.08);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 30px rgba(0,0,0,0.15);
}

.project-image {
    height: 200px;
    background: var(--gradient);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 3rem;
}

.project-content {
    padding: 1.5rem;
}

.project-title {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

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

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.tech-tag {
    background: var(--primary-color);
    color: white;
    padding: 0.2rem 0.6rem;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 500;
}

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

.project-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    color: var(--primary-color);
    font-weight: 500;
    transition: color 0.3s ease;
}

.project-link:hover {
    color: var(--secondary-color);
}

/* Blog Section */
.blog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.blog-card {
    background: var(--bg-white);
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 4px 20px rgba(0,0,0,0.08);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.blog-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 25px rgba(0,0,0,0.12);
}

.blog-date {
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-bottom: 0.5rem;
}

.blog-title {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.blog-excerpt {
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 1rem;
}

.blog-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.3rem;
    margin-bottom: 1rem;
}

.blog-tag {
    background: var(--bg-light);
    color: var(--text-secondary);
    padding: 0.2rem 0.6rem;
    border-radius: 12px;
    font-size: 0.75rem;
}

.read-more {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    gap: 0.3rem;
    transition: color 0.3s ease;
}

.read-more:hover {
    color: var(--secondary-color);
}

.publications-section {
  padding: 4rem 0;
  background-color: #f8f9fa;
}

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

.publication-item {
  background: white;
  padding: 2rem;
  margin-bottom: 2rem;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.publication-title {
  font-size: 1.3rem;
  margin-bottom: 0.5rem;
  color: #2c3e50;
}

.publication-meta {
  margin-bottom: 1rem;
  font-size: 0.9rem;
  color: #666;
}

.publication-meta span {
  margin-right: 1rem;
}

.type {
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  font-size: 0.8rem;
  font-weight: bold;
  text-transform: uppercase;
}

.type-journal { background-color: #e3f2fd; color: #1976d2; }
.type-conference { background-color: #f3e5f5; color: #7b1fa2; }
.type-workshop { background-color: #e8f5e8; color: #388e3c; }

.publication-abstract {
  margin-bottom: 1rem;
  line-height: 1.6;
  color: #555;
}

.publication-links a {
  display: inline-block;
  margin-right: 1rem;
  padding: 0.5rem 1rem;
  background-color: #007bff;
  color: white;
  text-decoration: none;
  border-radius: 4px;
  font-size: 0.9rem;
  transition: background-color 0.3s;
}

.publication-links a:hover {
  background-color: #0056b3;
}

/* Contact Section */
.contact-content {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-top: 2rem;
}

.contact-link {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-decoration: none;
    color: var(--text-primary);
    padding: 1rem;
    border-radius: 12px;
    transition: all 0.3s ease;
    background: var(--bg-white);
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.contact-link:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(0,0,0,0.1);
    color: var(--primary-color);
}

.contact-icon {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

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

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

/* Responsive Design */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .nav-links {
        flex-wrap: wrap;
        gap: 1rem;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1rem;
    }
    
    .contact-links {
        flex-direction: column;
        align-items: center;
    }
}

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

/* Loading animation for dynamic content */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid var(--border-color);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}