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

:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --dark-color: #1e293b;
    --light-color: #f8fafc;
    --text-color: #334155;
    --border-color: #e2e8f0;
    --success-color: #10b981;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    overflow-x: hidden;
}

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

/* Navbar */
.navbar {
    background: #fff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: all 0.3s ease;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 20px;
}

.nav-brand h2 {
    color: var(--primary-color);
    font-size: 1.5rem;
}

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

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

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

.nav-menu a.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--primary-color);
}

.admin-link {
    padding: 0.5rem 1rem;
    background: var(--primary-color);
    color: white !important;
    border-radius: 5px;
}

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

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

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 100px 0;
    color: white;
}

.hero-content {
    display: flex;
    align-items: center;
    gap: 4rem;
}

.hero-image {
    flex-shrink: 0;
}

.hero-image img {
    width: 250px;
    height: 250px;
    border-radius: 50%;
    object-fit: cover;
    border: 5px solid white;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
}

.hero-text h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.hero-text .title {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
    opacity: 0.95;
}

.hero-text .institution {
    font-size: 1.1rem;
    opacity: 0.9;
    margin-bottom: 2rem;
}

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

.social-links a {
    width: 45px;
    height: 45px;
    background: rgba(255,255,255,0.2);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.3rem;
    transition: all 0.3s ease;
}

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

/* Sections */
.section {
    padding: 80px 0;
}

.bg-light {
    background: var(--light-color);
}

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

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background: var(--primary-color);
    border-radius: 2px;
}

.subsection-title {
    font-size: 1.8rem;
    color: var(--dark-color);
    margin-top: 3rem;
    margin-bottom: 1.5rem;
}

/* About Section */
.about-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    font-size: 1.1rem;
    line-height: 1.8;
}

.research-interests {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: center;
    margin-top: 2rem;
}

.tag {
    background: var(--primary-color);
    color: white;
    padding: 0.7rem 1.5rem;
    border-radius: 25px;
    font-weight: 500;
    transition: transform 0.3s ease;
}

.tag:hover {
    transform: translateY(-3px);
}

/* Timeline */
.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    width: 2px;
    height: 100%;
    background: var(--border-color);
}

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
    display: flex;
}

.timeline-item:nth-child(odd) {
    justify-content: flex-end;
}

.timeline-item:nth-child(even) {
    justify-content: flex-start;
}

.timeline-dot {
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    width: 20px;
    height: 20px;
    background: var(--primary-color);
    border-radius: 50%;
    border: 4px solid white;
    box-shadow: 0 0 0 4px var(--border-color);
    z-index: 1;
}

.timeline-content {
    width: 45%;
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
}

.timeline-content h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.institution-name {
    font-weight: 600;
    color: var(--dark-color);
}

.year {
    color: #64748b;
    font-size: 0.9rem;
    margin: 0.5rem 0;
}

/* Publications */
.publications {
    max-width: 900px;
    margin: 0 auto;
}

.publication-item {
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 3px 15px rgba(0,0,0,0.08);
    margin-bottom: 2rem;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.publication-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 25px rgba(0,0,0,0.15);
}

.publication-item h3 {
    color: var(--dark-color);
    margin-bottom: 0.5rem;
}

.authors {
    color: #64748b;
    font-size: 0.95rem;
    margin-bottom: 0.3rem;
}

.venue {
    color: var(--text-color);
    font-style: italic;
    margin-bottom: 1rem;
}

.btn-link {
    display: inline-block;
    padding: 0.5rem 1.5rem;
    background: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 5px;
    transition: background 0.3s ease;
}

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

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

.project-card {
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 3px 15px rgba(0,0,0,0.08);
    transition: transform 0.3s ease;
}

.project-card:hover {
    transform: translateY(-5px);
}

.project-card h3 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.project-role {
    font-weight: 600;
    color: var(--dark-color);
    margin-bottom: 0.3rem;
}

.project-period {
    color: #64748b;
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

/* Courses Grid */
.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.course-card {
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 3px 15px rgba(0,0,0,0.08);
    text-align: center;
    transition: transform 0.3s ease;
}

.course-card:hover {
    transform: translateY(-5px);
}

.course-card i {
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.course-card h3 {
    color: var(--dark-color);
    margin-bottom: 0.5rem;
}

/* Contact Section */
.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
}

.contact-item {
    display: flex;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.contact-item i {
    font-size: 2rem;
    color: var(--primary-color);
}

.contact-item h4 {
    color: var(--dark-color);
    margin-bottom: 0.3rem;
}

.contact-form input,
.contact-form textarea {
    width: 100%;
    padding: 1rem;
    margin-bottom: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    font-family: inherit;
}

.contact-form textarea {
    resize: vertical;
}

.btn {
    background: var(--primary-color);
    color: white;
    padding: 1rem 2rem;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: background 0.3s ease;
}

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

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

/* Responsive */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 27px rgba(0,0,0,0.05);
        padding: 2rem 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .hero-content {
        flex-direction: column;
        text-align: center;
    }
    
    .hero-text h1 {
        font-size: 2rem;
    }
    
    .timeline::before {
        left: 30px;
    }
    
    .timeline-item {
        justify-content: flex-end !important;
        padding-left: 60px;
    }
    
    .timeline-dot {
        left: 30px;
        transform: none;
    }
    
    .timeline-content {
        width: 100%;
    }
    
    .contact-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
}