/* ===== CSS Variables & Design System ===== */
:root {
    /* Colors */
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-card: rgba(255, 255, 255, 0.03);
    --bg-glass: rgba(255, 255, 255, 0.05);

    --text-primary: #ffffff;
    --text-secondary: #a0a0b0;
    --text-muted: #6b6b7b;

    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --accent-tertiary: #06b6d4;
    --gradient-primary: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    --gradient-accent: linear-gradient(135deg, var(--accent-secondary), var(--accent-tertiary));

    /* Spacing */
    --section-padding: 100px 0;
    --container-width: 1200px;
    --card-radius: 16px;
    --border-radius-sm: 8px;

    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-medium: 0.3s ease;
    --transition-slow: 0.5s ease;

    /* Shadows */
    --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.3);
    --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.15);
}

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

html {
    scroll-behavior: smooth;
}

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

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== Navigation ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 20px 0;
    background: rgba(10, 10, 15, 0.8);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    transition: var(--transition-medium);
}

.nav-container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-decoration: none;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 40px;
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: var(--transition-fast);
    position: relative;
}

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

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-primary);
    transition: var(--transition-medium);
}

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

/* ===== Hero Section ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
}

#particles-canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    padding: 0 24px;
}

.hero-greeting {
    color: var(--accent-primary);
    font-size: 1.1rem;
    font-weight: 500;
    letter-spacing: 2px;
    text-transform: uppercase;
    margin-bottom: 16px;
    animation: fadeInUp 0.8s ease;
}

.hero-name {
    font-size: clamp(2.5rem, 8vw, 5rem);
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: 16px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: fadeInUp 0.8s ease 0.1s backwards;
}

.hero-title {
    font-size: clamp(1.5rem, 4vw, 2.5rem);
    font-weight: 300;
    color: var(--text-primary);
    margin-bottom: 12px;
    animation: fadeInUp 0.8s ease 0.2s backwards;
}

.hero-subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
    max-width: 600px;
    margin: 0 auto 40px;
    animation: fadeInUp 0.8s ease 0.3s backwards;
}

.hero-cta {
    display: flex;
    gap: 16px;
    justify-content: center;
    animation: fadeInUp 0.8s ease 0.4s backwards;
}

.btn {
    padding: 14px 32px;
    border-radius: 50px;
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    transition: var(--transition-medium);
    cursor: pointer;
    border: none;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: 0 4px 20px rgba(99, 102, 241, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 30px rgba(99, 102, 241, 0.5);
}

.btn-secondary {
    background: transparent;
    color: var(--text-primary);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: var(--accent-primary);
}

.scroll-indicator {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    animation: bounce 2s infinite;
}

.scroll-indicator span {
    display: block;
    width: 24px;
    height: 40px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 12px;
    position: relative;
}

.scroll-indicator span::before {
    content: '';
    position: absolute;
    top: 8px;
    left: 50%;
    transform: translateX(-50%);
    width: 4px;
    height: 8px;
    background: var(--accent-primary);
    border-radius: 2px;
    animation: scrollDown 2s infinite;
}

/* ===== Section Styles ===== */
section {
    padding: var(--section-padding);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 16px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: 60px;
}

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

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

.about-text {
    max-width: 700px;
}

.about-intro {
    font-size: 1.3rem;
    color: var(--text-primary);
    margin-bottom: 20px;
}

.about-text p {
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.about-text strong {
    color: var(--accent-primary);
}

.about-highlights {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.highlight-card {
    background: var(--bg-glass);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: var(--card-radius);
    padding: 24px;
    text-align: center;
    backdrop-filter: blur(10px);
    transition: var(--transition-medium);
}

.highlight-card:hover {
    border-color: var(--accent-primary);
    box-shadow: var(--shadow-glow);
}

.highlight-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.highlight-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

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

.timeline {
    position: relative;
    max-width: 800px;
    margin: 60px auto 0;
    padding-left: 40px;
}

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

.timeline-item {
    position: relative;
    padding-bottom: 50px;
    opacity: 0;
    transform: translateX(-20px);
    animation: slideInLeft 0.6s ease forwards;
}

.timeline-item:nth-child(1) {
    animation-delay: 0.1s;
}

.timeline-item:nth-child(2) {
    animation-delay: 0.2s;
}

.timeline-item:nth-child(3) {
    animation-delay: 0.3s;
}

.timeline-item:nth-child(4) {
    animation-delay: 0.4s;
}

.timeline-dot {
    position: absolute;
    left: -47px;
    width: 16px;
    height: 16px;
    background: var(--accent-primary);
    border-radius: 50%;
    border: 3px solid var(--bg-primary);
    box-shadow: 0 0 20px rgba(99, 102, 241, 0.5);
}

.timeline-content {
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.06);
    border-radius: var(--card-radius);
    padding: 28px;
    transition: var(--transition-medium);
}

.timeline-content:hover {
    border-color: var(--accent-primary);
    transform: translateX(8px);
}

.timeline-date {
    display: inline-block;
    background: var(--gradient-primary);
    color: white;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 12px;
}

.timeline-content h3 {
    font-size: 1.3rem;
    margin-bottom: 4px;
}

.timeline-content h4 {
    color: var(--accent-tertiary);
    font-weight: 500;
    margin-bottom: 12px;
}

.timeline-content p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

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

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
}

.project-card {
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.06);
    border-radius: var(--card-radius);
    overflow: hidden;
    transition: var(--transition-medium);
    cursor: pointer;
}

.project-card:hover {
    transform: translateY(-8px);
    border-color: var(--accent-primary);
    box-shadow: var(--shadow-glow);
}

.project-image {
    position: relative;
    height: 220px;
    overflow: hidden;
}

.project-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition-slow);
}

.project-card:hover .project-image img {
    transform: scale(1.05);
}

.project-overlay {
    position: absolute;
    inset: 0;
    background: rgba(99, 102, 241, 0.85);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: var(--transition-medium);
}

.project-card:hover .project-overlay {
    opacity: 1;
}

.view-project {
    color: white;
    font-weight: 600;
    padding: 12px 24px;
    border: 2px solid white;
    border-radius: 50px;
}

.project-info {
    padding: 24px;
}

.project-info h3 {
    font-size: 1.3rem;
    margin-bottom: 12px;
}

.project-info p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 16px;
}

.project-tags {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.tag {
    background: rgba(99, 102, 241, 0.15);
    color: var(--accent-primary);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
}

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

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 30px;
    margin-top: 60px;
}

.skill-category {
    background: var(--bg-glass);
    border: 1px solid rgba(255, 255, 255, 0.06);
    border-radius: var(--card-radius);
    padding: 32px;
    text-align: center;
    transition: var(--transition-medium);
}

.skill-category:hover {
    border-color: var(--accent-primary);
    transform: translateY(-4px);
}

.skill-icon {
    font-size: 2.5rem;
    margin-bottom: 16px;
}

.skill-category h3 {
    font-size: 1.1rem;
    margin-bottom: 20px;
    color: var(--text-primary);
}

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

.skill-list li {
    color: var(--text-secondary);
    padding: 8px 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    transition: var(--transition-fast);
}

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

.skill-list li:hover {
    color: var(--accent-primary);
}

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

.contact-text {
    color: var(--text-secondary);
    font-size: 1.2rem;
    max-width: 600px;
    margin: 0 auto 50px;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 30px;
    flex-wrap: wrap;
}

.contact-link {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px 28px;
    background: var(--bg-glass);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 50px;
    color: var(--text-primary);
    text-decoration: none;
    transition: var(--transition-medium);
}

.contact-link:hover {
    border-color: var(--accent-primary);
    transform: translateY(-4px);
    box-shadow: var(--shadow-glow);
}


/* ===== Modal ===== */
.modal {
    display: none;
    position: fixed;
    inset: 0;
    z-index: 2000;
    background: rgba(0, 0, 0, 0.9);
    backdrop-filter: blur(10px);
    align-items: center;
    justify-content: center;
    padding: 24px;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--bg-secondary);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--card-radius);
    max-width: 900px;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
    animation: modalFadeIn 0.3s ease;
}

.modal-close {
    position: absolute;
    top: 16px;
    right: 16px;
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 2rem;
    cursor: pointer;
    transition: var(--transition-fast);
    z-index: 10;
}

.modal-close:hover {
    color: var(--text-primary);
}

.modal-body {
    padding: 40px;
}

.modal-body h2 {
    font-size: 2rem;
    margin-bottom: 20px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.modal-body img {
    width: 100%;
    border-radius: var(--border-radius-sm);
    margin-bottom: 24px;
}

.modal-body p {
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.modal-body ul {
    color: var(--text-secondary);
    margin-left: 20px;
    margin-bottom: 16px;
}

.modal-body li {
    margin-bottom: 8px;
}

/* ===== Footer ===== */
.footer {
    background: var(--bg-primary);
    text-align: center;
    padding: 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.footer p {
    color: var(--text-muted);
    font-size: 0.9rem;
}

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

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInLeft {
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes bounce {

    0%,
    20%,
    50%,
    80%,
    100% {
        transform: translateX(-50%) translateY(0);
    }

    40% {
        transform: translateX(-50%) translateY(-10px);
    }

    60% {
        transform: translateX(-50%) translateY(-5px);
    }
}

@keyframes scrollDown {
    0% {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
    }

    100% {
        opacity: 0;
        transform: translateX(-50%) translateY(10px);
    }
}

@keyframes modalFadeIn {
    from {
        opacity: 0;
        transform: scale(0.9);
    }

    to {
        opacity: 1;
        transform: scale(1);
    }
}

/* ===== Dissertation Section ===== */
.dissertation {
    background: var(--bg-primary);
}

.dissertation-content {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 40px;
    align-items: start;
}

.dissertation-info {
    position: sticky;
    top: 100px;
}

.dissertation-info h3 {
    font-size: 1.5rem;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.dissertation-meta {
    color: var(--accent-tertiary);
    font-weight: 500;
    margin-bottom: 16px;
}

.dissertation-info>p {
    color: var(--text-secondary);
    margin-bottom: 20px;
}

.dissertation-highlights {
    list-style: none;
    margin-bottom: 24px;
}

.dissertation-highlights li {
    color: var(--text-secondary);
    padding: 8px 0;
    padding-left: 20px;
    position: relative;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

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

.dissertation-tags {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin-bottom: 24px;
}

.dissertation-download {
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.dissertation-viewer {
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: var(--card-radius);
    overflow: hidden;
    height: 700px;
}

.dissertation-viewer iframe {
    width: 100%;
    height: 100%;
    border: none;
}

/* ===== Responsive ===== */

/* Hamburger menu button (hidden on desktop) */
.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: space-between;
    width: 28px;
    height: 20px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0;
    z-index: 1001;
}

.nav-toggle span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: var(--transition-fast);
}

.nav-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translateY(6px) translateX(6px);
}

.nav-toggle.active span:nth-child(2) {
    opacity: 0;
}

.nav-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translateY(-6px) translateX(6px);
}

/* Tablet breakpoint */
@media (max-width: 1024px) {
    .dissertation-content {
        grid-template-columns: 1fr;
    }
    
    .dissertation-info {
        position: relative;
        top: 0;
    }
    
    .dissertation-viewer {
        height: 500px;
    }
}

/* Mobile breakpoint */
@media (max-width: 768px) {
    /* Show hamburger menu */
    .nav-toggle {
        display: flex;
    }
    
    /* Mobile navigation menu */
    .nav-links {
        display: none;
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: rgba(10, 10, 15, 0.98);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 32px;
        z-index: 1000;
    }
    
    .nav-links.active {
        display: flex;
    }
    
    .nav-links li {
        list-style: none;
    }
    
    .nav-links a {
        font-size: 1.5rem;
        padding: 12px 24px;
    }
    
    /* Prevent body scroll when nav is open */
    body.nav-open {
        overflow: hidden;
    }
    
    /* Hero section */
    .hero-content {
        padding: 0 16px;
    }
    
    .hero-subtitle {
        font-size: 1rem;
        margin-bottom: 32px;
    }
    
    .hero-cta {
        flex-direction: column;
        align-items: center;
        gap: 12px;
    }
    
    .hero-cta .btn {
        width: 100%;
        max-width: 280px;
        text-align: center;
    }
    
    /* Section padding */
    section {
        padding: 60px 0;
    }
    
    .container {
        padding: 0 16px;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .section-subtitle {
        margin-bottom: 40px;
    }
    
    /* About section */
    .about-content {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    
    .about-highlights {
        flex-direction: row;
        justify-content: center;
        flex-wrap: wrap;
    }
    
    .highlight-card {
        flex: 1;
        min-width: 140px;
    }
    
    /* Experience timeline */
    .timeline {
        padding-left: 24px;
        margin-top: 40px;
    }
    
    .timeline-dot {
        left: -31px;
        width: 12px;
        height: 12px;
    }
    
    .timeline-content {
        padding: 20px;
    }
    
    .timeline-content h3 {
        font-size: 1.1rem;
    }
    
    /* Projects grid */
    .projects-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .project-image {
        height: 180px;
    }
    
    .project-info {
        padding: 20px;
    }
    
    /* Skills grid */
    .skills-grid {
        grid-template-columns: 1fr 1fr;
        gap: 16px;
        margin-top: 40px;
    }
    
    .skill-category {
        padding: 20px;
    }
    
    .skill-icon {
        font-size: 2rem;
    }
    
    .skill-category h3 {
        font-size: 0.95rem;
        margin-bottom: 16px;
    }
    
    .skill-list li {
        padding: 6px 0;
        font-size: 0.9rem;
    }
    
    /* Dissertation section */
    .dissertation-content {
        grid-template-columns: 1fr;
        gap: 24px;
    }
    
    .dissertation-viewer {
        height: 400px;
    }
    
    /* Contact section */
    .contact-links {
        flex-direction: column;
        align-items: center;
        gap: 16px;
    }
    
    .contact-link {
        width: 100%;
        max-width: 300px;
        justify-content: center;
    }
    
    /* Modal improvements */
    .modal {
        padding: 16px;
    }
    
    .modal-content {
        max-height: 95vh;
        border-radius: 16px;
    }
    
    .modal-body {
        padding: 24px;
    }
    
    .modal-body h2 {
        font-size: 1.5rem;
    }
    
    .modal-close {
        top: 12px;
        right: 12px;
        font-size: 2.5rem;
        padding: 8px;
    }
    
    /* Scroll indicator hidden on mobile */
    .scroll-indicator {
        display: none;
    }
}

/* Small phone breakpoint */
@media (max-width: 480px) {
    .hero-name {
        font-size: 2.2rem;
    }
    
    .hero-title {
        font-size: 1.3rem;
    }
    
    .skills-grid {
        grid-template-columns: 1fr;
    }
    
    .highlight-card {
        min-width: 100%;
    }
    
    .about-highlights {
        flex-direction: column;
    }
    
    .dissertation-viewer {
        height: 300px;
    }
    
    .btn {
        padding: 12px 24px;
        font-size: 0.95rem;
    }
}