:root {
    --primary-color: #003262;
    --secondary-color: #FDB515;
    --text-dark: #2c3e50;
    --text-light: #6c757d;
    --bg-light: #f8f9fa;
    --bg-white: #ffffff;
    --border-color: #e9ecef;
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 25px rgba(0,0,0,0.1);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-white);
}

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

.navbar {
    background-color: var(--bg-white);
    box-shadow: var(--shadow-sm);
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
    text-decoration: none;
}

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

.nav-link {
    color: var(--text-dark);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-link:hover {
    color: var(--primary-color);
}

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

.bar {
    width: 25px;
    height: 3px;
    background-color: var(--text-dark);
    margin: 3px 0;
    transition: 0.3s;
}

.hero {
    padding: 120px 0 60px;
    background: var(--bg-white);
    min-height: calc(100vh - 200px);
    display: flex;
    align-items: center;
}

.hero-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 80px;
    align-items: center;
    max-width: 1100px;
    margin: 0 auto;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-light);
    margin-bottom: 1.5rem;
}

.hero-description {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-dark);
    margin-bottom: 2rem;
}

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

.btn {
    padding: 12px 28px;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s;
    display: inline-block;
}

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

.btn-primary:hover {
    background-color: #002244;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

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

.profile-img {
    width: 100%;
    max-width: 400px;
    height: auto;
    border-radius: 20px;
    box-shadow: var(--shadow-lg);
}

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

.about {
    padding: 80px 0;
    background-color: var(--bg-white);
}

.about-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 60px;
    align-items: start;
}

.about-text {
    font-size: 1.1rem;
    line-height: 1.8;
}

.about-text p {
    margin-bottom: 1.5rem;
}

.research-interests {
    list-style: none;
    margin-top: 1.5rem;
}

.research-interests li {
    padding: 0.5rem 0;
    display: flex;
    align-items: center;
    gap: 1rem;
}

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

.about-stats {
    display: grid;
    gap: 1.5rem;
}

.stat-card {
    background: var(--bg-light);
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    transition: transform 0.3s;
}

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

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.stat-label {
    color: var(--text-light);
    margin-top: 0.5rem;
}

.education {
    padding: 80px 0;
    background-color: var(--bg-white);
}

.education-timeline {
    position: relative;
    padding-left: 40px;
}

.education-timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 3px;
    background: linear-gradient(to bottom, var(--secondary-color), var(--primary-color));
}

.education-item {
    position: relative;
    margin-bottom: 3rem;
    padding-left: 30px;
}

.education-item::before {
    content: '';
    position: absolute;
    left: -41px;
    top: 5px;
    width: 15px;
    height: 15px;
    border-radius: 50%;
    background-color: var(--secondary-color);
    border: 3px solid var(--bg-white);
    box-shadow: 0 0 0 3px var(--secondary-color);
}

.education-date {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 6px 16px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.education-title {
    font-size: 1.4rem;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.education-institution {
    font-size: 1.1rem;
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 1rem;
}

.education-details {
    color: var(--text-light);
    line-height: 1.8;
}

.publications {
    padding: 60px 0 80px;
    background-color: var(--bg-light);
}

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

.filter-btn {
    padding: 10px 24px;
    background-color: white;
    border: 2px solid var(--border-color);
    border-radius: 25px;
    cursor: pointer;
    transition: all 0.3s;
    font-weight: 500;
}

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

.publications-grid {
    display: grid;
    gap: 2rem;
}

.publication-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s;
    border-left: 4px solid var(--secondary-color);
}

.publication-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateX(5px);
}

.publication-year {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 4px 12px;
    border-radius: 4px;
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.publication-title {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.publication-authors {
    color: var(--text-light);
    margin-bottom: 0.5rem;
}

.publication-venue {
    color: var(--text-light);
    margin-bottom: 1.5rem;
    font-style: italic;
}

.publication-venue i {
    margin-right: 0.5rem;
    color: var(--primary-color);
}

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

.pub-link {
    padding: 6px 14px;
    background-color: var(--bg-light);
    color: var(--text-dark);
    text-decoration: none;
    border-radius: 4px;
    font-size: 0.9rem;
    transition: all 0.3s;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

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

.contact {
    padding: 80px 0;
    background-color: var(--bg-white);
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
}

.contact-info h3,
.social-links h3 {
    margin-bottom: 2rem;
    color: var(--primary-color);
}

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

.contact-item i {
    color: var(--secondary-color);
    font-size: 1.2rem;
    width: 30px;
}

.contact-item a {
    color: var(--text-dark);
    text-decoration: none;
    transition: color 0.3s;
}

.contact-item a:hover {
    color: var(--primary-color);
}

.social-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
}

.social-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 12px 16px;
    background-color: var(--bg-light);
    color: var(--text-dark);
    text-decoration: none;
    border-radius: 8px;
    transition: all 0.3s;
}

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

.social-link i {
    font-size: 1.2rem;
}

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

@media screen and (max-width: 768px) {
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--shadow-lg);
        padding: 2rem 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-image {
        order: -1;
    }
    
    .profile-img {
        max-width: 250px;
    }
    
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .about-stats {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .contact-content {
        grid-template-columns: 1fr;
    }
    
    .social-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .education-timeline {
        padding-left: 20px;
    }
    
    .education-item {
        padding-left: 20px;
    }
    
    .education-item::before {
        left: -31px;
    }
}