/* ============================================
   CSS Variables & Root Styles
   ============================================ */
:root {
    /* Dark Theme Colors */
    --bg-primary: #0a0a0a;
    --bg-secondary: #111111;
    --bg-tertiary: #1a1a1a;
    --bg-glass: rgba(255, 255, 255, 0.05);
    --bg-glass-hover: rgba(255, 255, 255, 0.08);
    
    /* Accent Colors */
    --accent-primary: #00d9ff;
    --accent-secondary: #7b61ff;
    --accent-tertiary: #ff0080;
    --accent-gradient: linear-gradient(135deg, #00d9ff 0%, #7b61ff 50%, #ff0080 100%);
    
    /* Text Colors */
    --text-primary: #ffffff;
    --text-secondary: #b0b0b0;
    --text-tertiary: #808080;
    
    /* Border & Shadow */
    --border-color: 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);
    --shadow-glow: 0 0 20px rgba(0, 217, 255, 0.3);
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-secondary: 'Poppins', sans-serif;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
}

/* Light Theme (optional) */
[data-theme="light"] {
    --bg-primary: #ffffff;
    --bg-secondary: #f5f5f5;
    --bg-tertiary: #e8e8e8;
    --bg-glass: rgba(0, 0, 0, 0.05);
    --bg-glass-hover: rgba(0, 0, 0, 0.08);
    --text-primary: #0a0a0a;
    --text-secondary: #404040;
    --text-tertiary: #606060;
    --border-color: rgba(0, 0, 0, 0.1);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-primary);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ============================================
   Animated Background
   ============================================ */
.animated-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    overflow: hidden;
    pointer-events: none;
}

.gradient-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(40px);
    opacity: 0.2;
    animation: float 30s ease-in-out infinite;
}

.orb-1 {
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, var(--accent-primary) 0%, transparent 70%);
    top: -200px;
    left: -200px;
}

.orb-2 {
    width: 300px;
    height: 300px;
    background: radial-gradient(circle, var(--accent-secondary) 0%, transparent 70%);
    bottom: -150px;
    right: -150px;
}

.orb-3 {
    width: 250px;
    height: 250px;
    background: radial-gradient(circle, var(--accent-tertiary) 0%, transparent 70%);
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

@keyframes float {
    0%, 100% {
        transform: translate(0, 0);
    }
    50% {
        transform: translate(20px, -20px);
    }
}

@keyframes gradient-shift {
    0%, 100% {
        background-position: 0% 50%;
    }
    50% {
        background-position: 100% 50%;
    }
}

@keyframes float-up {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-20px);
    }
}

@keyframes rotate-slow {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

@keyframes shimmer-text {
    0% {
        background-position: -200% center;
    }
    100% {
        background-position: 200% center;
    }
}

/* ============================================
   Navigation
   ============================================ */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    padding: var(--spacing-sm) 0;
    background: rgba(10, 10, 10, 0.9);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    transition: all var(--transition-base);
}


.navbar.scrolled {
    padding: var(--spacing-xs) 0;
    box-shadow: var(--shadow-md);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo .logo-text {
    font-family: var(--font-secondary);
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-md);
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    position: relative;
    transition: color var(--transition-base);
    padding: var(--spacing-xs) 0;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-gradient);
    transition: width var(--transition-base);
}

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

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

.lang-toggle {
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: var(--spacing-xs) var(--spacing-sm);
    cursor: pointer;
    transition: all var(--transition-base);
    margin-left: var(--spacing-md);
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--accent-primary);
    backdrop-filter: blur(10px);
}

.lang-toggle:hover {
    background: var(--bg-glass-hover);
    transform: scale(1.05);
}

.lang-icon {
    position: relative;
    z-index: 1;
}

.theme-toggle {
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: var(--spacing-xs);
    cursor: pointer;
    transition: all var(--transition-base);
    margin-left: var(--spacing-md);
}

.theme-toggle:hover {
    background: var(--bg-glass-hover);
    transform: scale(1.1);
}

.hamburger {
    display: none;
    flex-direction: column;
    gap: 4px;
    cursor: pointer;
    padding: var(--spacing-xs);
}

.hamburger span {
    width: 25px;
    height: 2px;
    background: var(--text-primary);
    transition: all var(--transition-base);
}

/* ============================================
   Hero Section
   ============================================ */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md) 0;
    z-index: 1;
}

.hero-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    justify-content: center;
    align-items: center;
}

.hero-content {
    text-align: center;
    max-width: 800px;
    width: 100%;
}

.hero-photo {
    margin-bottom: var(--spacing-md);
    display: flex;
    justify-content: center;
}

.profile-photo {
    width: 240px;
    height: 240px;
    border-radius: var(--radius-md);
    object-fit: cover;
    object-position: center top;
    border: 4px solid var(--accent-primary);
    box-shadow: var(--shadow-glow);
    transition: transform var(--transition-base);
}

.profile-photo:hover {
    transform: scale(1.05);
}

.photo-placeholder {
    width: 240px;
    height: 240px;
    border-radius: var(--radius-md);
    background: var(--accent-gradient);
    display: flex;
    align-items: center;
    justify-content: center;
    border: 4px solid var(--accent-primary);
    box-shadow: var(--shadow-glow);
    margin: 0 auto;
}

.photo-placeholder span {
    font-size: 4rem;
    font-weight: 700;
    color: var(--text-primary);
    font-family: var(--font-secondary);
}

.hero-title {
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: var(--spacing-sm);
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: clamp(1.1rem, 2vw, 1.5rem);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    font-weight: 400;
}

.hero-description {
    color: var(--text-tertiary);
    margin-bottom: var(--spacing-md);
    font-size: 1.1rem;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    min-height: 44px;
    min-width: 120px;
    border-radius: var(--radius-md);
    text-decoration: none;
    font-weight: 600;
    transition: all var(--transition-base);
    border: none;
    cursor: pointer;
    font-size: 1rem;
    position: relative;
    overflow: hidden;
}


.btn-primary {
    background: var(--accent-gradient);
    color: var(--text-primary);
    box-shadow: var(--shadow-glow);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 0 20px rgba(0, 217, 255, 0.4);
}

.btn-primary:active {
    transform: translateY(-1px) scale(0.98);
}

.btn-secondary {
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: var(--bg-glass-hover);
    transform: translateY(-2px);
    border-color: var(--accent-primary);
    box-shadow: var(--shadow-md);
}

.btn-secondary:active {
    transform: translateY(-1px) scale(0.98);
}

.hero-contact-info {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    margin: var(--spacing-md) 0;
    align-items: center;
}

.contact-info-item {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    color: var(--text-secondary);
    text-decoration: none;
    transition: all var(--transition-base);
    padding: var(--spacing-sm) var(--spacing-md);
    min-height: 40px;
    border-radius: var(--radius-md);
    position: relative;
    overflow: hidden;
}

.contact-info-item:hover {
    color: var(--accent-primary);
    background: var(--bg-glass);
    transform: translateY(-2px);
}

.contact-info-item svg {
    width: 20px;
    height: 20px;
}

.hero-visual {
    animation: fadeInRight 1s ease-out;
}

.code-window {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    transform: perspective(1000px) rotateY(-5deg) rotateX(5deg);
    transition: transform var(--transition-base);
}

.code-window:hover {
    transform: perspective(1000px) rotateY(0deg) rotateX(0deg);
}

.code-header {
    background: var(--bg-tertiary);
    padding: var(--spacing-sm);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    border-bottom: 1px solid var(--border-color);
}

.code-dots {
    display: flex;
    gap: 6px;
}

.code-dots span {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--text-tertiary);
}

.code-dots span:nth-child(1) {
    background: #ff5f56;
}

.code-dots span:nth-child(2) {
    background: #ffbd2e;
}

.code-dots span:nth-child(3) {
    background: #27c93f;
}

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

.code-content {
    padding: var(--spacing-md);
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    line-height: 1.8;
    overflow-x: auto;
}

.code-content pre {
    margin: 0;
}

.code-keyword {
    color: #c792ea;
}

.code-string {
    color: #c3e88d;
}

.code-variable {
    color: #82aaff;
}

.code-number {
    color: #f78c6c;
}

.code-cursor {
    color: var(--accent-primary);
    animation: blink 1s infinite;
}

@keyframes blink {
    0%, 50% { opacity: 1; }
    51%, 100% { opacity: 0; }
}

.scroll-indicator {
    position: absolute;
    bottom: var(--spacing-md);
    left: 50%;
    transform: translateX(-50%);
    display: none;
}

.mouse {
    width: 30px;
    height: 50px;
    border: 2px solid var(--text-tertiary);
    border-radius: 15px;
    position: relative;
}

.wheel {
    width: 4px;
    height: 10px;
    background: var(--text-tertiary);
    border-radius: 2px;
    position: absolute;
    top: 10px;
    left: 50%;
    transform: translateX(-50%);
}

@keyframes bounce {
    0%, 100% { transform: translateX(-50%) translateY(0); }
    50% { transform: translateX(-50%) translateY(-10px); }
}

@keyframes scroll {
    0% { opacity: 1; transform: translateX(-50%) translateY(0); }
    100% { opacity: 0; transform: translateX(-50%) translateY(20px); }
}

/* ============================================
   Section Styles
   ============================================ */
section {
    position: relative;
    padding: var(--spacing-md) 0;
    z-index: 1;
}

.section-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.section-number {
    font-size: 4rem;
    font-weight: 700;
    color: var(--text-primary);
    opacity: 0.15;
    font-family: var(--font-secondary);
    text-shadow: 0 0 20px rgba(0, 217, 255, 0.3);
}

.section-title {
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 700;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Animated section titles only for about, publications, contact */
#about .section-title,
#publications .section-title,
#contact .section-title {
    position: relative;
}

.section-line {
    flex: 1;
    height: 1px;
    background: var(--border-color);
}

/* ============================================
   About Section
   ============================================ */
.about-content {
    display: grid;
    gap: var(--spacing-md);
}

.glass-card {
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    backdrop-filter: blur(10px);
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.glass-card:hover {
    background: var(--bg-glass-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.about-card h3 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.about-card p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
    line-height: 1.8;
}

.about-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.about-list li {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
    padding-left: var(--spacing-md);
    position: relative;
    line-height: 1.8;
}

.about-list li::before {
    content: '▹';
    position: absolute;
    left: 0;
    color: var(--accent-primary);
}

.about-highlights {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.highlight-item {
    text-align: center;
    padding: var(--spacing-md);
}

.highlight-item:nth-child(1) { --i: 0; }
.highlight-item:nth-child(2) { --i: 1; }
.highlight-item:nth-child(3) { --i: 2; }

.highlight-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-sm);
}

.highlight-item h4 {
    font-size: 1.2rem;
    margin-bottom: var(--spacing-xs);
    color: var(--accent-primary);
}

.highlight-item p {
    color: var(--text-tertiary);
    font-size: 0.9rem;
}

/* ============================================
   Skills Section
   ============================================ */
.skills-content {
    display: grid;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.skill-category {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    transition: all var(--transition-base);
}

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

.category-title {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 1.3rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.category-icon {
    font-size: 1.5rem;
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.skill-tag {
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.skill-tag::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: var(--skill-level, 0%);
    height: 100%;
    background: var(--accent-gradient);
    opacity: 0.2;
    transition: width var(--transition-slow);
    z-index: 0;
}

.skill-tag:hover {
    border-color: var(--accent-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

.skill-tag span {
    position: relative;
    z-index: 1;
}

.skills-visualization {
    display: grid;
    gap: var(--spacing-md);
}

.skill-bar-item {
    opacity: 0;
    transform: translateX(-20px);
    transition: all var(--transition-base);
}

.skill-bar-item.visible {
    opacity: 1;
    transform: translateX(0);
}

.skill-bar-label {
    display: flex;
    justify-content: space-between;
    margin-bottom: var(--spacing-xs);
    font-weight: 500;
}

.skill-percentage {
    color: var(--accent-primary);
}

.skill-bar {
    height: 8px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    overflow: hidden;
    position: relative;
}

.skill-bar-fill {
    height: 100%;
    background: var(--accent-gradient);
    border-radius: var(--radius-sm);
    width: 0;
    transition: width 1.5s ease-out;
    position: relative;
}


/* ============================================
   Education Section
   ============================================ */
.education {
    position: relative;
    padding: var(--spacing-xl) 0;
    z-index: 1;
}

/* ============================================
   Projects Section
   ============================================ */
.projects {
    position: relative;
    padding: var(--spacing-xl) 0;
    z-index: 1;
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-md);
}

.project-card {
    padding: var(--spacing-md);
    transition: all var(--transition-base);
    display: flex;
    flex-direction: column;
    height: 100%;
}

.project-card:hover {
    transform: translateY(-5px);
}

.project-card .project-link {
    margin-top: auto;
    align-self: flex-start;
}

.project-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-sm);
    text-align: center;
}

.project-title {
    font-size: 1.3rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.project-description {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1.8;
}

.project-list {
    list-style: none;
    padding: 0;
    margin: var(--spacing-sm) 0;
}

.project-list li {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
    padding-left: var(--spacing-md);
    position: relative;
    line-height: 1.6;
}

.project-list li::before {
    content: '▹';
    position: absolute;
    left: 0;
    color: var(--accent-primary);
}

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.project-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    min-height: 40px;
    color: var(--accent-primary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    border: 1px solid var(--accent-primary);
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.project-link:hover {
    background: var(--accent-primary);
    color: var(--text-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-glow);
}

.project-link:active {
    transform: translateY(-1px) scale(1.02);
}

.project-link svg {
    width: 16px;
    height: 16px;
}

/* ============================================
   Publications Section
   ============================================ */
.publications {
    position: relative;
    padding: var(--spacing-xl) 0;
    z-index: 1;
}

.publications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-md);
}

.publication-card {
    padding: var(--spacing-md);
    transition: all var(--transition-base);
    text-align: center;
    display: flex;
    flex-direction: column;
    height: 100%;
}

.publication-card:hover {
    transform: translateY(-5px);
}

.publication-card .publication-link {
    margin-top: auto;
    align-self: center;
}

.publication-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-sm);
}

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

.publication-type {
    color: var(--accent-primary);
    font-size: 0.9rem;
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.publication-topic {
    color: var(--text-primary);
    font-size: 1rem;
    margin-bottom: var(--spacing-sm);
    line-height: 1.6;
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--bg-glass);
    border-left: 3px solid var(--accent-primary);
    border-radius: var(--radius-sm);
}

.publication-topic strong {
    color: var(--accent-primary);
    font-weight: 600;
}

.publication-description {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1.8;
    font-size: 0.95rem;
}

.publication-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    min-height: 44px;
    min-width: 140px;
    color: var(--accent-primary);
    text-decoration: none;
    font-weight: 500;
    border: 1px solid var(--accent-primary);
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.publication-link:hover {
    background: var(--accent-primary);
    color: var(--text-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-glow);
}

.publication-link:active {
    transform: translateY(-1px) scale(1.02);
}

.publication-link svg {
    width: 18px;
    height: 18px;
}

/* ============================================
   Experience Section
   ============================================ */
.timeline {
    position: relative;
    padding-left: var(--spacing-md);
}

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

.timeline-item {
    position: relative;
    margin-bottom: var(--spacing-lg);
    padding-left: var(--spacing-lg);
}

.timeline-marker {
    position: absolute;
    left: -9px;
    top: 0;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--accent-gradient);
    border: 3px solid var(--bg-primary);
    box-shadow: var(--shadow-glow);
}

.timeline-content {
    /* No animation */
    opacity: 1;
}

.timeline-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    margin-bottom: var(--spacing-xs);
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.timeline-title {
    font-size: 1.5rem;
    color: var(--text-primary);
}

.timeline-company {
    color: var(--accent-primary);
    font-weight: 600;
}

.timeline-period {
    display: block;
    color: var(--text-tertiary);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-sm);
}

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

.timeline-list {
    list-style: none;
    padding-left: var(--spacing-md);
    margin: var(--spacing-sm) 0;
}

.timeline-list li {
    position: relative;
    padding-left: var(--spacing-md);
    margin-bottom: var(--spacing-xs);
    color: var(--text-secondary);
}

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

.timeline-tech {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-md);
}

.tech-tag {
    padding: 4px var(--spacing-xs);
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    color: var(--accent-primary);
}

/* ============================================
   Contact Section
   ============================================ */
.contact-content {
    display: flex;
    justify-content: center;
}

.contact-card {
    max-width: 600px;
    text-align: center;
    padding: var(--spacing-lg);
}

.contact-card h3 {
    font-size: 2rem;
    margin-bottom: var(--spacing-sm);
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.contact-card p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

.social-links {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    flex-wrap: wrap;
}

.social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    min-height: 44px;
    min-width: 140px;
    background: var(--bg-glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    text-decoration: none;
    transition: all var(--transition-base);
    backdrop-filter: blur(10px);
    position: relative;
    overflow: hidden;
}

.social-link:hover {
    background: var(--bg-glass-hover);
    border-color: var(--accent-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-glow);
}

.social-link:active {
    transform: translateY(-1px) scale(1.02);
}

.social-link svg {
    width: 20px;
    height: 20px;
}

.btn-download {
    margin-top: var(--spacing-md);
    background: var(--accent-gradient);
    color: var(--text-primary);
    box-shadow: var(--shadow-glow);
}

.btn-download:hover {
    transform: translateY(-2px);
    box-shadow: 0 0 20px rgba(0, 217, 255, 0.4);
}

.btn-download:active {
    transform: translateY(-1px) scale(0.98);
}

/* ============================================
   Footer
   ============================================ */
.footer {
    text-align: center;
    padding: var(--spacing-md) 0;
    border-top: 1px solid var(--border-color);
    color: var(--text-tertiary);
    font-size: 0.9rem;
}

.heart {
    color: var(--accent-tertiary);
}

/* ============================================
   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 fadeInLeft {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* ============================================
   Additional Animations
   ============================================ */
.skill-tag {
    position: relative;
}

@keyframes shine {
    0% { left: -100%; }
    100% { left: 100%; }
}

@keyframes glow-pulse {
    0%, 100% {
        box-shadow: 0 0 5px rgba(0, 217, 255, 0.2);
    }
    50% {
        box-shadow: 0 0 15px rgba(0, 217, 255, 0.5);
    }
}

.tech-tag {
    transition: all var(--transition-base);
    position: relative;
}

.tech-tag:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

.project-icon {
    display: inline-block;
}

.publication-icon {
    display: inline-block;
}

.timeline-marker {
    /* No animation */
    opacity: 1;
}

.section-number {
    color: var(--text-primary);
    opacity: 0.15;
    text-shadow: 0 0 20px rgba(0, 217, 255, 0.3);
}

/* Animated section numbers only for about, publications, contact */
#about .section-number,
#publications .section-number,
#contact .section-number {
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    opacity: 0.6;
    text-shadow: none;
}

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

/* Extra Small Devices (phones, 320px and up) */
@media (max-width: 480px) {
    :root {
        --spacing-xs: 0.25rem;
        --spacing-sm: 0.5rem;
        --spacing-md: 1rem;
        --spacing-lg: 1.5rem;
        --spacing-xl: 2rem;
    }
    
    .hero-title {
        font-size: 1.8rem;
    }
    
    .hero-subtitle {
        font-size: 0.9rem;
    }
    
    .section-title {
        font-size: 1.5rem;
    }
    
    .section-number {
        font-size: 1.5rem;
    }
    
    .nav-menu {
        padding: var(--spacing-sm);
    }
    
    .btn {
        min-width: 100px;
        font-size: 0.9rem;
        padding: var(--spacing-xs) var(--spacing-sm);
    }
    
    .project-card,
    .publication-card {
        padding: var(--spacing-sm);
    }
    
    .profile-photo,
    .photo-placeholder {
        width: 120px;
        height: 120px;
    }
    
    .photo-placeholder span {
        font-size: 2rem;
    }
}

/* Small Devices (landscape phones, 481px and up) */
@media (min-width: 481px) and (max-width: 767px) {
    :root {
        --spacing-md: 1.5rem;
        --spacing-lg: 2.5rem;
        --spacing-xl: 3rem;
    }
}

/* Medium Devices (tablets, 768px and up) */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        flex-direction: column;
        background: var(--bg-secondary);
        width: 100%;
        text-align: center;
        transition: left var(--transition-base);
        padding: var(--spacing-md);
        border-top: 1px solid var(--border-color);
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .hero-container {
        flex-direction: column;
    }
    
    .hero-content {
        text-align: center;
    }
    
    .profile-photo,
    .photo-placeholder {
        width: 180px;
        height: 180px;
    }
    
    .photo-placeholder span {
        font-size: 3rem;
    }
    
    .projects-grid,
    .publications-grid {
        grid-template-columns: 1fr;
    }
    
    .section-header {
        flex-wrap: wrap;
    }
    
    .section-number {
        font-size: 2rem;
    }
    
    .about-highlights {
        grid-template-columns: 1fr;
    }
    
    .hero-buttons {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
    
    .social-links {
        flex-direction: column;
    }
    
    .social-link {
        width: 100%;
        justify-content: center;
    }
    
    .lang-toggle,
    .theme-toggle {
        margin-left: var(--spacing-xs);
        padding: var(--spacing-xs);
    }
    
    .nav-container {
        padding: 0 var(--spacing-sm);
    }
}

/* Large Devices (desktops, 1024px and up) */
@media (min-width: 1024px) {
    .container {
        max-width: 1200px;
    }
    
    .projects-grid {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .publications-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Extra Large Devices (large desktops, 1440px and up) */
@media (min-width: 1440px) {
    .container {
        max-width: 1400px;
    }
    
    .hero-container {
        max-width: 1400px;
    }
}

/* Landscape Orientation */
@media (orientation: landscape) and (max-height: 600px) {
    .hero {
        min-height: auto;
        padding: var(--spacing-md) 0;
    }
    
    section {
        padding: var(--spacing-md) 0;
    }
}

/* High DPI Displays */
@media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) {
    .profile-photo {
        image-rendering: -webkit-optimize-contrast;
        image-rendering: crisp-edges;
    }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Touch Device Optimizations */
@media (hover: none) and (pointer: coarse) {
    .btn,
    .project-link,
    .publication-link,
    .social-link {
        min-height: 48px;
        padding: var(--spacing-sm) var(--spacing-md);
    }
    
    .nav-link {
        padding: var(--spacing-sm);
    }
    
    .glass-card:hover {
        transform: none;
    }
}

/* Print Styles */
@media print {
    .animated-bg,
    .scroll-indicator,
    .navbar,
    .theme-toggle,
    .lang-toggle,
    .hamburger {
        display: none !important;
    }
    
    body {
        background: white;
        color: black;
    }
    
    section {
        page-break-inside: avoid;
    }
}

/* ============================================
   Utility Classes
   ============================================ */
.visible {
    opacity: 1 !important;
    transform: translateY(0) !important;
}

.fade-in {
    animation: fadeInUp 0.6s ease-out;
}