:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --secondary-color: #f59e0b;
    --accent-color: #10b981;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-dark: #111827;
    --bg-dark-secondary: #1f2937;
    --border-color: #e5e7eb;
    --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);
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --gradient-accent: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
}

[data-theme="dark"] {
    --text-primary: #f9fafb;
    --text-secondary: #d1d5db;
    --text-light: #9ca3af;
    --bg-primary: #111827;
    --bg-secondary: #1f2937;
    --bg-dark: #ffffff;
    --bg-dark-secondary: #f9fafb;
    --border-color: #374151;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: all 0.3s ease;
    overflow-x: hidden;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--primary-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary-dark);
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: all 0.3s ease;
}

[data-theme="dark"] .navbar {
    background: rgba(17, 24, 39, 0.95);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

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

.logo:hover {
    transform: scale(1.05);
}

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

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

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

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

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

.theme-toggle {
    background: none;
    border: 2px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.5rem;
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.3s ease;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle:hover {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.5rem;
    cursor: pointer;
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
    position: relative;
    overflow: hidden;
}

.hero::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 1000 1000"><defs><radialGradient id="a" cx="50%" cy="50%"><stop offset="0%" stop-color="%236366f1" stop-opacity="0.1"/><stop offset="100%" stop-color="%236366f1" stop-opacity="0"/></radialGradient></defs><circle cx="200" cy="200" r="300" fill="url(%23a)"/><circle cx="800" cy="300" r="200" fill="url(%23a)"/><circle cx="400" cy="700" r="250" fill="url(%23a)"/></svg>') no-repeat center center;
    background-size: cover;
    opacity: 0.3;
}

.hero-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-content h1 {
    font-size: 3.5rem;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1rem;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: fadeInUp 1s ease;
}

.hero-content .subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    animation: fadeInUp 1s ease 0.2s both;
}

.hero-content .description {
    font-size: 1.1rem;
    color: var(--text-light);
    margin-bottom: 2rem;
    line-height: 1.7;
    animation: fadeInUp 1s ease 0.4s both;
}

.cta-buttons {
    display: flex;
    gap: 1rem;
    animation: fadeInUp 1s ease 0.6s both;
}

.btn {
    padding: 0.875rem 2rem;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

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

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

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

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

.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
    animation: fadeInRight 1s ease 0.8s both;
}

.hero-image-placeholder {
    width: 300px;
    height: 300px;
    background: var(--gradient-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    color: white;
    box-shadow: var(--shadow-xl);
    position: relative;
    overflow: hidden;
}

.hero-image-placeholder::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: linear-gradient(45deg, transparent, rgba(255,255,255,0.1), transparent);
    animation: shimmer 3s infinite;
}

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

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

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

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

.about-text {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-secondary);
}

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

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.skill-category {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: 1rem;
    text-align: center;
    transition: transform 0.3s ease;
    border: 1px solid var(--border-color);
}

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

.skill-category h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.2rem;
}

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

.skill-tag {
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
}

/* Projects Section */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.project-card {
    background: var(--bg-secondary);
    border-radius: 1rem;
    overflow: hidden;
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
}

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

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

.project-content {
    padding: 2rem;
}

.project-title {
    font-size: 1.25rem;
    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: 1.5rem;
}

.tech-tag {
    background: var(--accent-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.75rem;
    font-weight: 500;
}

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

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

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

/* Education Section */
.education-content {
    max-width: 800px;
    margin: 0 auto;
}

.education-item {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: 1rem;
    margin-bottom: 2rem;
    border: 1px solid var(--border-color);
    transition: transform 0.3s ease;
}

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

.education-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.education-header h3 {
    color: var(--primary-color);
    font-size: 1.25rem;
    margin: 0;
}

.education-year {
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
}

.education-institution {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

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

.education-gpa {
    color: var(--accent-color);
    font-weight: 600;
}

/* Research Section */
.research-content {
    max-width: 1000px;
    margin: 0 auto;
}

.research-item {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: 1rem;
    margin-bottom: 2rem;
    border: 1px solid var(--border-color);
    transition: transform 0.3s ease;
}

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

.research-item h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

.research-list, .awards-list {
    list-style: none;
    padding: 0;
}

.research-list li, .awards-list li {
    margin-bottom: 1rem;
    padding-left: 1rem;
    position: relative;
    color: var(--text-secondary);
    line-height: 1.6;
}

.research-list li::before, .awards-list li::before {
    content: '•';
    color: var(--primary-color);
    font-weight: bold;
    position: absolute;
    left: 0;
}

.publication-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.publication-item {
    background: var(--bg-primary);
    padding: 1.5rem;
    border-radius: 0.5rem;
    border-left: 4px solid var(--primary-color);
}

.publication-item p {
    margin-bottom: 0.5rem;
}

.publication-item p:first-child {
    color: var(--text-primary);
    font-weight: 600;
}

.publication-item p:nth-child(2) {
    color: var(--text-secondary);
}

.publication-item p:last-child {
    color: var(--text-light);
    font-style: italic;
}

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

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

.contact-info h3 {
    color: var(--text-primary);
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.5rem;
    color: var(--text-secondary);
}

.contact-item i {
    color: var(--primary-color);
    width: 20px;
}

.contact-form {
    background: var(--bg-primary);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    font-weight: 500;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.875rem;
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 1rem;
    transition: border-color 0.3s ease;
    background: var(--bg-primary);
    color: var(--text-primary);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

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

.social-links {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.social-link {
    color: var(--text-light);
    font-size: 1.5rem;
    transition: color 0.3s ease;
}

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

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

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

@keyframes shimmer {
    0% {
        transform: translateX(-100%) translateY(-100%) rotate(45deg);
    }
    100% {
        transform: translateX(100%) translateY(100%) rotate(45deg);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .mobile-menu-toggle {
        display: block;
    }

    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        height: calc(100vh - 70px);
        background: var(--bg-primary);
        flex-direction: column;
        justify-content: start;
        align-items: center;
        padding-top: 2rem;
        transition: left 0.3s ease;
    }

    .nav-menu.active {
        left: 0;
    }

    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 2rem;
    }

    .hero-content h1 {
        font-size: 2.5rem;
    }

    .cta-buttons {
        justify-content: center;
        flex-wrap: wrap;
    }

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

    .contact-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

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

    .education-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }

    .education-year {
        align-self: flex-start;
    }

    .research-item {
        padding: 1.5rem;
    }

    .publication-item {
        padding: 1rem;
    }
}

@media (max-width: 480px) {
    .hero-content h1 {
        font-size: 2rem;
    }

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

    .container {
        padding: 0 1rem;
    }

    .nav-container {
        padding: 0 1rem;
    }
}

/* Loading Animation */
.loading {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--bg-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    transition: opacity 0.5s ease;
}

.loading.hidden {
    opacity: 0;
    pointer-events: none;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 3px solid var(--border-color);
    border-top: 3px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}