:root {
    /* Modern elegant color scheme */
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary: #0891b2;
    --accent: #f59e0b;
    --bg-white: #ffffff;
    --bg-light: #f8fafc;
    --bg-gray: #f1f5f9;
    --text-dark: #0f172a;
    --text-gray: #475569;
    --text-light: #64748b;
    --border: #e2e8f0;
    
    /* Typography */
    --font-display: 'Playfair Display', Georgia, serif;
    --font-body: 'Work Sans', system-ui, sans-serif;
    
    /* Spacing */
    --container-width: 1200px;
    --section-padding: 5rem;
    --card-padding: 2rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    color: var(--text-dark);
    line-height: 1.7;
    background: var(--bg-white);
}

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 2rem;
}

/* Header */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
    z-index: 1000;
    transition: all 0.3s ease;
}

.header-container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 1.25rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-dark);
    text-decoration: none;
    transition: color 0.3s ease;
}

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

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

.nav-link {
    color: var(--text-gray);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.3s ease;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary);
    transition: width 0.3s ease;
}

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

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 5px;
}

.menu-toggle span {
    width: 25px;
    height: 2px;
    background: var(--text-dark);
    transition: all 0.3s ease;
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding: 8rem 0 4rem;
    background: linear-gradient(135deg, #f8fafc 0%, #e0f2fe 100%);
}

.hero-container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 2rem;
}

.hero-content {
    max-width: 800px;
}

.hero-greeting {
    font-size: 1.25rem;
    color: var(--primary);
    font-weight: 500;
    margin-bottom: 0.5rem;
    animation: fadeInUp 0.6s ease;
}

.hero-name {
    font-family: var(--font-display);
    font-size: clamp(3rem, 7vw, 5rem);
    font-weight: 900;
    color: var(--text-dark);
    line-height: 1.1;
    margin-bottom: 1rem;
    animation: fadeInUp 0.6s ease 0.2s both;
}

.hero-title {
    font-size: clamp(1.5rem, 3vw, 2rem);
    color: var(--text-gray);
    font-weight: 600;
    margin-bottom: 1.5rem;
    animation: fadeInUp 0.6s ease 0.4s both;
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: 2rem;
    animation: fadeInUp 0.6s ease 0.6s both;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    margin-bottom: 3rem;
    animation: fadeInUp 0.6s ease 0.8s both;
    flex-wrap: wrap;
}

.btn {
    padding: 0.875rem 2rem;
    font-weight: 600;
    font-size: 1rem;
    text-decoration: none;
    border-radius: 8px;
    transition: all 0.3s ease;
    display: inline-block;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

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

.hero-stats {
    display: flex;
    gap: 3rem;
    animation: fadeInUp 0.6s ease 1s both;
}

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

.stat-number {
    display: block;
    font-family: var(--font-display);
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary);
    line-height: 1;
}

.stat-label {
    display: block;
    font-size: 0.95rem;
    color: var(--text-gray);
    margin-top: 0.5rem;
}

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

/* Section Styling */
section {
    padding: var(--section-padding) 0;
}

.section-title {
    font-family: var(--font-display);
    font-size: clamp(2.5rem, 5vw, 3.5rem);
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 3rem;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 0;
    width: 60px;
    height: 4px;
    background: var(--primary);
}

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

.about-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 4rem;
}

.text-large {
    font-size: 1.25rem;
    line-height: 1.8;
    color: var(--text-dark);
    font-weight: 500;
    margin-bottom: 1.5rem;
}

.about-text p {
    color: var(--text-gray);
    margin-bottom: 1.25rem;
}

.about-highlights {
    margin-top: 2rem;
    display: grid;
    gap: 1.5rem;
}

.highlight h3 {
    font-size: 1.25rem;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.highlight p {
    color: var(--text-light);
    line-height: 1.6;
}

.about-info {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.info-card {
    background: var(--bg-light);
    padding: var(--card-padding);
    border-radius: 12px;
    border: 1px solid var(--border);
}

.info-card h3 {
    font-size: 1.25rem;
    color: var(--text-dark);
    margin-bottom: 1.5rem;
    font-weight: 600;
}

.info-list {
    list-style: none;
}

.info-list li {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border);
    color: var(--text-gray);
}

.info-list li:last-child {
    border-bottom: none;
}

.info-icon {
    font-size: 1.25rem;
}

.link {
    color: var(--primary);
    text-decoration: none;
    font-weight: 500;
}

.link:hover {
    text-decoration: underline;
}

.expertise-list {
    list-style: none;
}

.expertise-list li {
    padding: 0.5rem 0;
    color: var(--text-gray);
    position: relative;
    padding-left: 1.5rem;
}

.expertise-list li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--primary);
    font-weight: 700;
}

/* Experience Section */
.experience {
    background: var(--bg-light);
}

.timeline {
    position: relative;
    padding-left: 3rem;
}

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

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

.timeline-item::before {
    content: '';
    position: absolute;
    left: -3.5rem;
    top: 0.5rem;
    width: 12px;
    height: 12px;
    background: var(--primary);
    border-radius: 50%;
    border: 3px solid var(--bg-light);
}

.timeline-date {
    font-weight: 600;
    color: var(--primary);
    margin-bottom: 0.5rem;
    font-size: 0.95rem;
}

.timeline-content {
    background: var(--bg-white);
    padding: var(--card-padding);
    border-radius: 12px;
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

.timeline-content:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-5px);
}

.timeline-content h3 {
    font-size: 1.5rem;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.timeline-content h4 {
    font-size: 1.1rem;
    color: var(--text-gray);
    font-weight: 500;
    margin-bottom: 1rem;
}

.timeline-content > p {
    color: var(--text-light);
    margin-bottom: 1rem;
}

.timeline-content ul {
    list-style: none;
    margin-bottom: 1.5rem;
}

.timeline-content li {
    position: relative;
    padding-left: 1.5rem;
    margin-bottom: 0.75rem;
    color: var(--text-gray);
}

.timeline-content li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--primary);
}

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

.tag {
    padding: 0.4rem 1rem;
    background: var(--bg-light);
    color: var(--primary);
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
    border: 1px solid var(--border);
}

/* Projects Section */
.projects {
    background: var(--bg-white);
}

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

.project-card {
    background: var(--bg-white);
    padding: var(--card-padding);
    border-radius: 12px;
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

.project-card:hover {
    box-shadow: var(--shadow-xl);
    transform: translateY(-10px);
    border-color: var(--primary);
}

.project-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.project-card h3 {
    font-size: 1.5rem;
    color: var(--text-dark);
    margin-bottom: 1rem;
    font-weight: 600;
}

.project-card p {
    color: var(--text-gray);
    line-height: 1.7;
    margin-bottom: 1.5rem;
}

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

.project-tech span {
    padding: 0.4rem 0.875rem;
    background: var(--bg-light);
    color: var(--text-gray);
    border-radius: 6px;
    font-size: 0.85rem;
    font-weight: 500;
}

/* Skills Section */
.skills {
    background: var(--bg-light);
}

.skills-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.skill-group {
    background: var(--bg-white);
    padding: var(--card-padding);
    border-radius: 12px;
    border: 1px solid var(--border);
}

.skill-group h3 {
    font-size: 1.25rem;
    color: var(--text-dark);
    margin-bottom: 1.5rem;
    font-weight: 600;
}

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

.skill-tags span {
    padding: 0.5rem 1rem;
    background: var(--bg-light);
    color: var(--text-gray);
    border-radius: 6px;
    font-size: 0.9rem;
    border: 1px solid var(--border);
    transition: all 0.3s ease;
}

.skill-tags span:hover {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

.certifications {
    background: var(--bg-white);
    padding: var(--card-padding);
    border-radius: 12px;
    border: 1px solid var(--border);
}

.certifications h3 {
    font-size: 1.5rem;
    color: var(--text-dark);
    margin-bottom: 1.5rem;
    font-weight: 600;
}

.cert-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1rem;
}

.cert-item {
    padding: 1rem;
    background: var(--bg-light);
    border-radius: 8px;
    color: var(--text-gray);
}

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

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

.publication {
    display: flex;
    gap: 2rem;
    padding: var(--card-padding);
    background: var(--bg-light);
    border-radius: 12px;
    border: 1px solid var(--border);
    transition: all 0.3s ease;
}

.publication:hover {
    box-shadow: var(--shadow-lg);
}

.pub-year {
    font-family: var(--font-display);
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary);
    opacity: 0.5;
    flex-shrink: 0;
}

.pub-details h3 {
    font-size: 1.25rem;
    color: var(--text-dark);
    margin-bottom: 0.75rem;
    font-weight: 600;
}

.pub-authors {
    color: var(--text-light);
    font-size: 0.95rem;
    margin-bottom: 0.5rem;
}

.pub-venue {
    color: var(--text-gray);
    font-size: 0.95rem;
    margin-bottom: 1rem;
}

.pub-link {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.95rem;
}

.pub-link:hover {
    text-decoration: underline;
}

/* Blog Section */
.blog {
    background: var(--bg-light);
}

.section-description {
    color: var(--text-gray);
    font-size: 1.125rem;
    margin-bottom: 3rem;
    max-width: 700px;
}

.blog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 2rem;
}

.blog-card {
    background: var(--bg-white);
    padding: var(--card-padding);
    border-radius: 12px;
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
}

.blog-card:hover {
    box-shadow: var(--shadow-xl);
    transform: translateY(-10px);
    border-color: var(--primary);
}

.blog-category {
    display: inline-block;
    padding: 0.4rem 1rem;
    background: var(--bg-light);
    color: var(--primary);
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 1rem;
    align-self: flex-start;
}

.blog-title {
    font-size: 1.5rem;
    color: var(--text-dark);
    margin-bottom: 1rem;
    font-weight: 600;
    line-height: 1.4;
}

.blog-excerpt {
    color: var(--text-gray);
    line-height: 1.7;
    margin-bottom: 1.5rem;
    flex-grow: 1;
}

.blog-meta {
    display: flex;
    gap: 1.5rem;
    margin-bottom: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border);
}

.blog-date,
.blog-read-time {
    font-size: 0.875rem;
    color: var(--text-light);
}

.blog-link {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.3s ease;
}

.blog-link:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

/* Contact Section */
.contact {
    background: var(--bg-light);
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
}

.contact-text {
    max-width: 600px;
}

.contact-text p {
    color: var(--text-gray);
    margin-top: 1.5rem;
}

.contact-info {
    display: grid;
    gap: 1.5rem;
}

.contact-card {
    display: flex;
    gap: 1.5rem;
    padding: 1.5rem;
    background: var(--bg-white);
    border-radius: 12px;
    border: 1px solid var(--border);
    transition: all 0.3s ease;
}

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

.contact-icon {
    font-size: 2rem;
    flex-shrink: 0;
}

.contact-card h4 {
    font-size: 0.875rem;
    color: var(--text-light);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 0.5rem;
}

.contact-card a {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
}

.contact-card a:hover {
    text-decoration: underline;
}

.contact-card p {
    color: var(--text-gray);
    font-weight: 500;
}

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

.footer-content {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.footer-content p {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.95rem;
}

/* Responsive Design */
@media (max-width: 968px) {
    .about-grid,
    .contact-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .nav-list {
        display: none;
    }
    
    .menu-toggle {
        display: flex;
    }
    
    .nav.active .nav-list {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: white;
        border-top: 1px solid var(--border);
        padding: 2rem;
        box-shadow: var(--shadow-lg);
    }
    
    .hero-stats {
        flex-wrap: wrap;
        gap: 2rem;
    }
}

@media (max-width: 640px) {
    :root {
        --section-padding: 3rem;
        --card-padding: 1.5rem;
    }
    
    .hero {
        padding: 6rem 0 3rem;
    }
    
    .hero-buttons {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        text-align: center;
    }
    
    .projects-grid,
    .skills-container {
        grid-template-columns: 1fr;
    }
    
    .timeline {
        padding-left: 2rem;
    }
    
    .timeline-item::before {
        left: -2.5rem;
    }
    
    .publication {
        flex-direction: column;
    }
}