/* CSS Variables for Theme */
:root {
    --primary: #4361ee;
    --secondary: #3a0ca3;
    --accent: #f72585;
    --light: #f8f9fa;
    --dark: #212529;
    --gray: #6c757d;
    --light-gray: #e9ecef;
    --success: #4cc9f0;
    --warning: #ffba08;
    
    --gradient-primary: linear-gradient(135deg, #4361ee 0%, #3a0ca3 100%);
    --gradient-accent: linear-gradient(135deg, #f72585 0%, #b5179e 100%);
    --gradient-light: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.15);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.2);
    
    --border-radius: 12px;
    --border-radius-lg: 20px;
    
    --transition: all 0.3s ease;
    --glass-bg: rgba(255, 255, 255, 0.1);
    --glass-border: rgba(255, 255, 255, 0.2);
}

/* Dark Mode */
@media (prefers-color-scheme: dark) {
    :root {
        --light: #121212;
        --dark: #f8f9fa;
        --gray: #adb5bd;
        --light-gray: #2d3748;
        --glass-bg: rgba(255, 255, 255, 0.05);
        --glass-border: rgba(255, 255, 255, 0.1);
        --shadow-sm: 0 2px 8px rgba(0,0,0,0.3);
        --shadow-md: 0 4px 16px rgba(0,0,0,0.4);
        --shadow-lg: 0 8px 32px rgba(0,0,0,0.5);
    }
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    line-height: 1.6;
    color: var(--dark);
    background-color: var(--light);
    transition: var(--transition);
}

/* Container */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Typography */
h1, h2, h3, h4 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1rem;
}

h1 { font-size: 3.5rem; }
h2 { font-size: 2.5rem; }
h3 { font-size: 1.75rem; }
h4 { font-size: 1.25rem; }

p { margin-bottom: 1rem; }

.section-title {
    text-align: center;
    margin-bottom: 3rem;
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: var(--gradient-accent);
    border-radius: 2px;
}

.subsection-title {
    text-align: center;
    margin: 3rem 0 1.5rem;
    color: var(--primary);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 12px 28px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

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

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

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

.btn-secondary:hover {
    background: var(--primary);
    color: white;
    transform: translateY(-3px);
}

/* Navigation */
.header {
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
}

@media (prefers-color-scheme: dark) {
    .header {
        background: rgba(18, 18, 18, 0.95);
    }
}

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

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

.logo span {
    color: var(--accent);
}

.menu-toggle {
    display: none;
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    padding: 10px;
}

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

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

.nav-link {
    text-decoration: none;
    color: var(--dark);
    font-weight: 500;
    transition: var(--transition);
    padding: 5px 10px;
    border-radius: 5px;
}

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

#home:target ~ .header .nav-link[href="#home"],
#about:target ~ .header .nav-link[href="#about"],
#skills:target ~ .header .nav-link[href="#skills"],
#experience:target ~ .header .nav-link[href="#experience"],
#education:target ~ .header .nav-link[href="#education"],
#publications:target ~ .header .nav-link[href="#publications"],
#courses:target ~ .header .nav-link[href="#courses"],
#projects:target ~ .header .nav-link[href="#projects"],
#certifications:target ~ .header .nav-link[href="#certifications"],
#gallery:target ~ .header .nav-link[href="#gallery"],
#testimonials:target ~ .header .nav-link[href="#testimonials"],
#contact:target ~ .header .nav-link[href="#contact"] {
    background: var(--primary);
    color: white;
}

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

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

/* Hero */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: var(--gradient-primary);
    color: white;
    padding-top: 80px;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: float 20s infinite linear;
}

@keyframes float {
    0% { transform: translate(0, 0) rotate(0deg); }
    100% { transform: translate(-50%, -50%) rotate(360deg); }
}

.hero-content {
    text-align: center;
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 4rem;
    margin-bottom: 0.5rem;
    animation: fadeInUp 1s ease;
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    opacity: 0.9;
    animation: fadeInUp 1s ease 0.2s both;
}

.hero-tagline {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.8;
    animation: fadeInUp 1s ease 0.4s both;
}

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

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 3rem;
    flex-wrap: wrap;
    animation: fadeInUp 1s ease 0.8s both;
}

.stat {
    text-align: center;
}

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

.stat-label {
    font-size: 0.9rem;
    opacity: 0.9;
}

/* About */
.about-grid {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 3rem;
    align-items: center;
}

.profile-circle {
    width: 300px;
    height: 300px;
    border-radius: 50%;
    background: var(--gradient-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto;
    animation: float 3s ease-in-out infinite;
}

.profile-initials {
    font-size: 4rem;
    font-weight: 700;
    color: white;
}

.about-text {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
}

.about-details {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
    margin-top: 2rem;
}

.detail {
    padding: 0.75rem;
    background: var(--glass-bg);
    border-radius: var(--border-radius);
    border: 1px solid var(--glass-border);
}

/* Skills */
.skills-grid {
    display: grid;
    gap: 2rem;
    margin-bottom: 3rem;
}

.skill-category {
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    border-radius: var(--border-radius);
    padding: 2rem;
}

.skill-items {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin: 1rem 0;
}

.skill-chip {
    padding: 0.5rem 1rem;
    background: var(--primary);
    color: white;
    border-radius: 50px;
    font-size: 0.9rem;
    font-weight: 500;
}

.progress-container {
    margin-top: 1.5rem;
}

.progress-label {
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.5rem;
}

.progress-bar {
    height: 10px;
    background: var(--light-gray);
    border-radius: 5px;
    overflow: hidden;
}

.progress-bar span {
    display: block;
    height: 100%;
    background: var(--gradient-accent);
    border-radius: 5px;
    animation: progress 1.5s ease-in-out;
}

@keyframes progress {
    from { width: 0; }
}

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

.tech-card {
    text-align: center;
    padding: 2rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

@media (prefers-color-scheme: dark) {
    .tech-card {
        background: var(--light-gray);
    }
}

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

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

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

.timeline::before {
    content: '';
    position: absolute;
    left: 30px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--primary);
}

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
    padding-left: 80px;
}

.timeline-date {
    position: absolute;
    left: 0;
    top: 0;
    background: var(--primary);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    font-weight: 600;
}

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

@media (prefers-color-scheme: dark) {
    .timeline-content {
        background: var(--light-gray);
    }
}

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

.timeline-list {
    list-style-position: inside;
}

.timeline-list li {
    margin-bottom: 0.5rem;
}

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

.education-card {
    padding: 2rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    border-left: 4px solid var(--primary);
}

@media (prefers-color-scheme: dark) {
    .education-card {
        background: var(--light-gray);
    }
}

.education-year {
    color: var(--accent);
    font-weight: 600;
    margin-bottom: 0.5rem;
}

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

.education-details {
    color: var(--gray);
    font-size: 0.9rem;
}

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

.publication-card {
    padding: 2rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

@media (prefers-color-scheme: dark) {
    .publication-card {
        background: var(--light-gray);
    }
}

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

.publication-venue {
    color: var(--primary);
    font-weight: 600;
    margin-bottom: 1rem;
    font-size: 0.9rem;
}

.publication-abstract {
    color: var(--gray);
    margin-bottom: 1.5rem;
    font-size: 0.95rem;
}

.publication-link {
    color: var(--accent);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
}

.publications-cta {
    text-align: center;
}

/* Courses */
.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.course-card {
    text-align: center;
    padding: 2rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

@media (prefers-color-scheme: dark) {
    .course-card {
        background: var(--light-gray);
    }
}

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

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

/* Projects */
.project-filters {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 3rem;
}

.project-filters input {
    display: none;
}

.filter-btn {
    padding: 0.5rem 1.5rem;
    background: var(--light-gray);
    border-radius: 50px;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

.filter-btn:hover,
#all:checked ~ label[for="all"],
#web:checked ~ label[for="web"],
#tools:checked ~ label[for="tools"],
#research:checked ~ label[for="research"] {
    background: var(--primary);
    color: white;
}

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

.project-card {
    padding: 2rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    opacity: 1;
    transform: scale(1);
}

@media (prefers-color-scheme: dark) {
    .project-card {
        background: var(--light-gray);
    }
}

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

#web:checked ~ .projects-grid .project-card:not([data-category="web"]),
#tools:checked ~ .projects-grid .project-card:not([data-category="tools"]),
#research:checked ~ .projects-grid .project-card:not([data-category="research"]) {
    opacity: 0.3;
    transform: scale(0.95);
}

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin: 1rem 0;
}

.tech-tag {
    padding: 0.25rem 0.75rem;
    background: var(--light-gray);
    border-radius: 50px;
    font-size: 0.8rem;
    color: var(--primary);
}

.project-links {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
}

.project-link {
    color: var(--accent);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
}

/* Certifications */
.certifications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.cert-card {
    text-align: center;
    padding: 2rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

@media (prefers-color-scheme: dark) {
    .cert-card {
        background: var(--light-gray);
    }
}

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

.cert-badge {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.cert-issuer {
    color: var(--primary);
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.cert-id {
    color: var(--gray);
    font-size: 0.85rem;
}

/* Gallery */
.gallery-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.gallery-item {
    height: 250px;
    border-radius: var(--border-radius);
    background: var(--gradient);
    position: relative;
    overflow: hidden;
    transition: var(--transition);
}

.gallery-item:hover {
    transform: scale(1.05);
}

.gallery-label {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(0, 0, 0, 0.8);
    color: white;
    padding: 1rem;
    transform: translateY(100%);
    transition: var(--transition);
}

.gallery-item:hover .gallery-label {
    transform: translateY(0);
}

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

.testimonial-card {
    padding: 2rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    position: relative;
}

@media (prefers-color-scheme: dark) {
    .testimonial-card {
        background: var(--light-gray);
    }
}

.testimonial-card::before {
    content: '"';
    font-size: 4rem;
    color: var(--primary);
    opacity: 0.2;
    position: absolute;
    top: 0.5rem;
    left: 1rem;
}

.testimonial-text {
    font-style: italic;
    margin-bottom: 1.5rem;
    position: relative;
    z-index: 1;
}

.testimonial-author {
    border-top: 1px solid var(--light-gray);
    padding-top: 1rem;
}

/* Contact */
.contact-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 3rem;
}

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

.contact-card {
    padding: 1.5rem;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    text-align: center;
}

@media (prefers-color-scheme: dark) {
    .contact-card {
        background: var(--light-gray);
    }
}

.contact-icon {
    font-size: 2rem;
    margin-bottom: 1rem;
}

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

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--light-gray);
    border-radius: var(--border-radius);
    font-family: inherit;
    background: var(--light);
    color: var(--dark);
    transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.1);
}

.form-note {
    margin-top: 1rem;
    color: var(--gray);
    font-size: 0.9rem;
    text-align: center;
}

/* Footer */
.footer {
    background: var(--dark);
    color: white;
    padding: 3rem 0;
}

.footer-content {
    text-align: center;
}

.footer-social {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.social-link {
    color: white;
    text-decoration: none;
    opacity: 0.8;
    transition: var(--transition);
}

.social-link:hover {
    opacity: 1;
    color: var(--accent);
}

.footer-copyright {
    margin-bottom: 0.5rem;
    opacity: 0.8;
}

.footer-credit {
    opacity: 0.6;
    font-size: 0.9rem;
}

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

/* Print Styles */
@media print {
    .header,
    .hero-buttons,
    .contact-form,
    .footer,
    .project-filters {
        display: none;
    }
    
    body {
        font-size: 12pt;
        color: black;
        background: white;
    }
    
    .container {
        max-width: 100%;
        padding: 0;
    }
    
    .section {
        padding: 2rem 0;
        break-inside: avoid;
    }
    
    .btn {
        display: none;
    }
    
    a {
        color: black;
        text-decoration: none;
    }
}

/* Responsive */
@media (max-width: 1024px) {
    h1 { font-size: 3rem; }
    h2 { font-size: 2.25rem; }
    .hero-title { font-size: 3.5rem; }
}

@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        top: 80px;
        left: -100%;
        width: 100%;
        flex-direction: column;
        background: white;
        padding: 2rem;
        box-shadow: var(--shadow-lg);
        transition: 0.3s;
    }
    
    @media (prefers-color-scheme: dark) {
        .nav-menu {
            background: var(--light);
        }
    }
    
    .menu-toggle:checked ~ .nav-menu {
        left: 0;
    }
    
    .hero-title { font-size: 2.75rem; }
    .hero-subtitle { font-size: 1.25rem; }
    .hero-buttons { flex-direction: column; align-items: center; }
    .hero-stats { gap: 1.5rem; }
    
    .about-grid {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .profile-circle {
        width: 200px;
        height: 200px;
    }
    
    .about-details {
        grid-template-columns: 1fr;
    }
    
    .timeline::before {
        left: 20px;
    }
    
    .timeline-item {
        padding-left: 60px;
    }
    
    .timeline-date {
        position: relative;
        margin-bottom: 1rem;
        display: inline-block;
    }
}

@media (max-width: 480px) {
    h1 { font-size: 2.5rem; }
    h2 { font-size: 2rem; }
    h3 { font-size: 1.5rem; }
    
    .hero-title { font-size: 2.25rem; }
    .hero-subtitle { font-size: 1.1rem; }
    .hero-tagline { font-size: 1rem; }
    
    .stat-number { font-size: 2rem; }
    .stat-label { font-size: 0.8rem; }
    
    .container {
        padding: 0 15px;
    }
    
    .projects-grid,
    .publications-grid,
    .courses-grid,
    .certifications-grid,
    .testimonials-grid {
        grid-template-columns: 1fr;
    }
    
    .contact-grid {
        grid-template-columns: 1fr;
    }
}