/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-accent: #eff6ff;
    --border-color: #e5e7eb;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1);
}

html {
    scroll-behavior: smooth;
}

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

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

/* Navigation */
.nav {
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    text-decoration: none;
}

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

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

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

/* Hero Section */
.hero {
    padding: 6rem 0;
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-accent) 100%);
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 4rem;
    align-items: center;
}

.hero-image img {
    width: 100%;
    max-width: 300px;
    border-radius: 20px;
    box-shadow: var(--shadow-xl);
    border: 4px solid white;
}

.hero-text h1 {
    font-size: 3rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.affiliation {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.research-interests {
    font-size: 1rem;
    color: var(--primary-color);
    font-weight: 500;
    margin-bottom: 2rem;
}

.hero-stats {
    display: grid;
    gap: 1rem;
    margin-bottom: 2rem;
    padding: 1.5rem;
    background: white;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.stat {
    display: flex;
    flex-direction: column;
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.stat-value {
    font-size: 1rem;
    color: var(--text-primary);
    font-weight: 600;
    margin-top: 0.25rem;
}

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

.btn-primary,
.btn-secondary {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 500;
    text-decoration: none;
    transition: all 0.2s;
}

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

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

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

.btn-secondary:hover {
    background: var(--bg-accent);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* Sections */
.section {
    padding: 5rem 0;
}

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

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

.about-content {
    max-width: 800px;
    margin: 0 auto;
}

.lead {
    font-size: 1.25rem;
    line-height: 1.8;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
}

.about-content p {
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

/* Research Section */
.research-section {
    background: var(--bg-secondary);
}

.research-card {
    background: white;
    padding: 3rem;
    border-radius: 16px;
    box-shadow: var(--shadow-lg);
    max-width: 900px;
    margin: 0 auto;
}

.research-title {
    font-size: 1.75rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
}

.research-description p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

.research-list {
    list-style: none;
    margin: 1rem 0 1rem 1rem;
}

.research-list li {
    padding: 0.5rem 0;
    position: relative;
    padding-left: 1.5rem;
}

.research-list li::before {
    content: "→";
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

.research-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-top: 2rem;
}

.tag {
    padding: 0.5rem 1rem;
    background: var(--bg-accent);
    color: var(--primary-color);
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
}

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

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

.project-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    transition: all 0.3s;
}

.project-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.project-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.project-meta {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-style: italic;
}

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

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

.tag-small {
    padding: 0.25rem 0.75rem;
    background: var(--bg-secondary);
    color: var(--text-secondary);
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 500;
}

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

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

.timeline-item {
    display: grid;
    grid-template-columns: 200px 1fr;
    gap: 2rem;
    margin-bottom: 3rem;
    position: relative;
}

.timeline-item::before {
    content: "";
    position: absolute;
    left: 200px;
    top: 8px;
    width: 12px;
    height: 12px;
    background: var(--primary-color);
    border-radius: 50%;
    transform: translateX(-6px);
}

.timeline-item::after {
    content: "";
    position: absolute;
    left: 200px;
    top: 20px;
    bottom: -3rem;
    width: 2px;
    background: var(--border-color);
    transform: translateX(-1px);
}

.timeline-item:last-child::after {
    display: none;
}

.timeline-date {
    font-weight: 600;
    color: var(--primary-color);
    font-size: 0.875rem;
}

.timeline-content {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.timeline-content h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.timeline-org {
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.timeline-gpa {
    font-size: 0.875rem;
    color: var(--primary-color);
    font-weight: 500;
    margin-bottom: 1rem;
}

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

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

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

.timeline-list li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

.timeline-courses {
    margin-top: 1rem;
    cursor: pointer;
}

.timeline-courses summary {
    font-weight: 500;
    color: var(--primary-color);
    padding: 0.5rem;
    border-radius: 6px;
    transition: background 0.2s;
}

.timeline-courses summary:hover {
    background: var(--bg-secondary);
}

.timeline-courses ul {
    list-style: none;
    margin-top: 1rem;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0.5rem;
}

.timeline-courses li {
    padding: 0.5rem;
    background: var(--bg-secondary);
    border-radius: 6px;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* Achievements Section */
.achievements-section {
    background: var(--bg-primary);
}

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

.achievement-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    border: 2px solid var(--border-color);
    transition: all 0.3s;
}

.achievement-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.achievement-card.highlight {
    background: linear-gradient(135deg, var(--bg-accent) 0%, white 100%);
    border-color: var(--primary-color);
}

.achievement-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.achievement-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.achievement-card p {
    color: var(--text-secondary);
    line-height: 1.7;
}

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

.contact-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.contact-intro {
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 3rem;
}

.contact-methods {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.contact-method {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: all 0.3s;
}

.contact-method:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.contact-icon {
    width: 60px;
    height: 60px;
    margin: 0 auto 1rem;
    background: var(--bg-accent);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
}

.contact-method h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

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

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

.contact-method p {
    color: var(--text-secondary);
}

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

.footer p {
    margin-bottom: 0.5rem;
}

.footer-note {
    font-size: 0.875rem;
    opacity: 0.7;
}

/* Responsive Design */
@media (max-width: 968px) {
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-image img {
        margin: 0 auto;
    }

    .contact-links {
        justify-content: center;
    }

    .timeline-item {
        grid-template-columns: 1fr;
    }

    .timeline-item::before,
    .timeline-item::after {
        display: none;
    }

    .timeline-courses ul {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .hero-text h1 {
        font-size: 2rem;
    }

    .subtitle {
        font-size: 1.25rem;
    }

    .section-title {
        font-size: 2rem;
    }

    .projects-grid {
        grid-template-columns: 1fr;
    }

    .achievements-grid {
        grid-template-columns: 1fr;
    }

    .contact-methods {
        grid-template-columns: 1fr;
    }
}

/* Smooth Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.section {
    animation: fadeIn 0.6s ease-out;
}