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

:root {
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-card: #1a1a2e;
    --bg-card-hover: #1f1f35;
    --text-primary: #e4e4e7;
    --text-secondary: #a1a1aa;
    --text-muted: #71717a;
    --accent: #6366f1;
    --accent-light: #818cf8;
    --accent-glow: rgba(99, 102, 241, 0.3);
    --accent-bg: rgba(99, 102, 241, 0.1);
    --accent-gradient: linear-gradient(135deg, #6366f1, #8b5cf6);
    --border: #27273a;
    --border-light: #3f3f5c;
    --nav-bg: rgba(10, 10, 15, 0.8);
    --nav-bg-scroll: rgba(10, 10, 15, 0.95);
    --hero-name-gradient: linear-gradient(135deg, #fff 0%, #a1a1aa 100%);
    --card-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    --card-shadow-hover: 0 10px 40px rgba(0, 0, 0, 0.2);
    --radius: 12px;
    --radius-sm: 8px;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
}

[data-theme="light"] {
    --bg-primary: #f8f9fa;
    --bg-secondary: #ffffff;
    --bg-card: #ffffff;
    --bg-card-hover: #f0f0f5;
    --text-primary: #1a1a2e;
    --text-secondary: #4a4a5a;
    --text-muted: #71717a;
    --accent: #6366f1;
    --accent-light: #818cf8;
    --accent-glow: rgba(99, 102, 241, 0.15);
    --accent-bg: rgba(99, 102, 241, 0.08);
    --accent-gradient: linear-gradient(135deg, #6366f1, #8b5cf6);
    --border: #e2e2ea;
    --border-light: #d1d1db;
    --nav-bg: rgba(248, 249, 250, 0.8);
    --nav-bg-scroll: rgba(248, 249, 250, 0.95);
    --hero-name-gradient: linear-gradient(135deg, #1a1a2e 0%, #4a4a6a 100%);
    --card-shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
    --card-shadow-hover: 0 10px 40px rgba(99, 102, 241, 0.1);
}

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

body {
    font-family: var(--font-main);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    overflow-x: hidden;
    position: relative;
}

/* Starfield background (dark mode only) */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    background-image:
        radial-gradient(1px 1px at 10% 20%, rgba(255,255,255,0.5), transparent),
        radial-gradient(1px 1px at 20% 50%, rgba(255,255,255,0.3), transparent),
        radial-gradient(1.5px 1.5px at 30% 10%, rgba(255,255,255,0.6), transparent),
        radial-gradient(1px 1px at 40% 70%, rgba(255,255,255,0.4), transparent),
        radial-gradient(1.5px 1.5px at 50% 40%, rgba(255,255,255,0.5), transparent),
        radial-gradient(1px 1px at 60% 80%, rgba(255,255,255,0.3), transparent),
        radial-gradient(2px 2px at 70% 15%, rgba(255,255,255,0.6), transparent),
        radial-gradient(1px 1px at 80% 60%, rgba(255,255,255,0.4), transparent),
        radial-gradient(1.5px 1.5px at 90% 30%, rgba(255,255,255,0.5), transparent),
        radial-gradient(1px 1px at 15% 85%, rgba(255,255,255,0.3), transparent),
        radial-gradient(1px 1px at 25% 45%, rgba(255,255,255,0.4), transparent),
        radial-gradient(2px 2px at 35% 95%, rgba(255,255,255,0.5), transparent),
        radial-gradient(1px 1px at 45% 25%, rgba(255,255,255,0.3), transparent),
        radial-gradient(1.5px 1.5px at 55% 75%, rgba(255,255,255,0.6), transparent),
        radial-gradient(1px 1px at 65% 5%, rgba(255,255,255,0.4), transparent),
        radial-gradient(1px 1px at 75% 55%, rgba(255,255,255,0.3), transparent),
        radial-gradient(2px 2px at 85% 85%, rgba(255,255,255,0.5), transparent),
        radial-gradient(1px 1px at 95% 45%, rgba(255,255,255,0.4), transparent),
        radial-gradient(1px 1px at 5% 65%, rgba(255,255,255,0.3), transparent),
        radial-gradient(1.5px 1.5px at 48% 12%, rgba(255,255,255,0.5), transparent);
    animation: starfield-drift 60s linear infinite;
}

@keyframes starfield-drift {
    0% { transform: translateY(0); }
    100% { transform: translateY(-30px); }
}

[data-theme="light"] body::before {
    display: none;
}

a {
    color: var(--accent-light);
    text-decoration: none;
    transition: color var(--transition);
}

a:hover {
    color: var(--accent);
}

/* ===== Navigation ===== */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: var(--nav-bg);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid transparent;
    transition: border-color var(--transition), background var(--transition);
}

.nav.scrolled {
    border-bottom-color: var(--border);
    background: var(--nav-bg-scroll);
}

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

.nav-logo {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--text-primary);
    letter-spacing: -0.02em;
    font-family: var(--font-mono);
    -webkit-text-fill-color: var(--text-primary);
}

.logo-dot {
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    font-weight: 700;
}

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

.nav-links a {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    position: relative;
    padding: 0.25rem 0;
}

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

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

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

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    transition: var(--transition);
}

/* ===== Theme Toggle Button ===== */
.theme-toggle {
    background: none;
    border: 1px solid var(--border);
    color: var(--text-primary);
    cursor: pointer;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition);
    font-size: 1.15rem;
}

.theme-toggle:hover {
    border-color: var(--accent);
    color: var(--accent);
    transform: rotate(30deg);
}

.theme-toggle .icon-sun {
    display: none;
}

.theme-toggle .icon-moon {
    display: inline;
}

[data-theme="light"] .theme-toggle .icon-moon {
    display: none;
}

[data-theme="light"] .theme-toggle .icon-sun {
    display: inline;
}

/* ===== Hero Section ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    padding: 2rem;
}

.hero-bg {
    position: absolute;
    inset: 0;
    overflow: hidden;
}

.particles {
    position: absolute;
    inset: 0;
}

.particle {
    position: absolute;
    border-radius: 50%;
    background: #fff;
    opacity: 0;
    animation: twinkle-move 8s infinite ease-in-out;
}

.particle:nth-child(odd) {
    width: 2px;
    height: 2px;
}

.particle:nth-child(even) {
    width: 1px;
    height: 1px;
}

.particle:nth-child(3n) {
    width: 3px;
    height: 3px;
    box-shadow: 0 0 6px rgba(255, 255, 255, 0.4);
}

@keyframes twinkle-move {
    0% { opacity: 0; transform: translate(0, 0); }
    20% { opacity: 0.8; }
    50% { opacity: 0.3; transform: translate(30px, -60px); }
    80% { opacity: 0.7; }
    100% { opacity: 0; transform: translate(60px, -120px); }
}

.hero-content {
    text-align: center;
    z-index: 1;
    max-width: 800px;
}

.hero-greeting {
    font-size: 1.1rem;
    color: var(--accent-light);
    font-weight: 500;
    margin-bottom: 0.5rem;
    opacity: 0;
    animation: fadeInUp 0.8s ease forwards;
}

.hero-name {
    font-size: clamp(2.5rem, 6vw, 4.5rem);
    font-weight: 700;
    letter-spacing: -0.03em;
    line-height: 1.1;
    margin-bottom: 1rem;
    background: var(--hero-name-gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    opacity: 0;
    animation: fadeInUp 0.8s ease 0.2s forwards;
}

.hero-title-wrapper {
    font-size: clamp(1.2rem, 3vw, 1.8rem);
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    height: 2.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    opacity: 0;
    animation: fadeInUp 0.8s ease 0.4s forwards;
}

.hero-title-dynamic {
    color: var(--accent-light);
    font-weight: 600;
}

.cursor {
    animation: blink 1s infinite;
    color: var(--accent);
    font-weight: 300;
}

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

.hero-description {
    font-size: 1.05rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 2rem;
    line-height: 1.8;
    opacity: 0;
    animation: fadeInUp 0.8s ease 0.6s forwards;
}

.hero-cta {
    display: flex;
    gap: 1rem;
    justify-content: center;
    opacity: 0;
    animation: fadeInUp 0.8s ease 0.8s forwards;
}

.hero-socials {
    display: flex;
    gap: 1.2rem;
    justify-content: center;
    margin-top: 1.5rem;
    opacity: 0;
    animation: fadeInUp 0.8s ease 1s forwards;
}

.hero-socials a {
    color: var(--text-secondary);
    transition: color var(--transition), transform var(--transition);
}

.hero-socials a:hover {
    color: var(--accent);
    transform: translateY(-3px);
}

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

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    padding: 0.75rem 2rem;
    border-radius: 50px;
    font-size: 0.95rem;
    font-weight: 500;
    transition: all var(--transition);
    cursor: pointer;
    border: none;
}

.btn-primary {
    background: var(--accent-gradient);
    color: #fff;
    box-shadow: 0 4px 20px var(--accent-glow);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 30px var(--accent-glow);
    color: #fff;
}

.btn-outline {
    border: 1.5px solid var(--border-light);
    color: var(--text-primary);
    background: transparent;
}

.btn-outline:hover {
    border-color: var(--accent);
    color: var(--accent-light);
    transform: translateY(-2px);
}

/* ===== Scroll Indicator ===== */
.scroll-indicator {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    opacity: 0;
    animation: fadeInUp 0.8s ease 1.2s forwards;
}

.scroll-arrow {
    width: 24px;
    height: 24px;
    border-right: 2px solid var(--text-muted);
    border-bottom: 2px solid var(--text-muted);
    transform: rotate(45deg);
    animation: scrollBounce 2s infinite;
}

@keyframes scrollBounce {
    0%, 100% { transform: rotate(45deg) translate(0, 0); opacity: 0.5; }
    50% { transform: rotate(45deg) translate(5px, 5px); opacity: 1; }
}

/* ===== Sections ===== */
.section {
    padding: 6rem 2rem;
}

.section-alt {
    background: var(--bg-secondary);
}

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

.section-title {
    font-size: 2rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    position: relative;
    letter-spacing: -0.02em;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: var(--accent-gradient);
    margin: 0.75rem auto 0;
    border-radius: 2px;
}

/* ===== About Section ===== */
.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.about-text p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-size: 1.05rem;
}

.about-stats {
    display: flex;
    gap: 2rem;
    margin-top: 2rem;
}

.stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
}

.stat-number {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-light);
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* ===== Code Window ===== */
.code-window {
    background: var(--bg-card);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    overflow: hidden;
    box-shadow: var(--card-shadow);
}

.code-header {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 12px 16px;
    background: rgba(255, 255, 255, 0.03);
    border-bottom: 1px solid var(--border);
}

.dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
}

.dot.red { background: #ff5f57; }
.dot.yellow { background: #febc2e; }
.dot.green { background: #28c840; }

.code-filename {
    margin-left: auto;
    font-size: 0.8rem;
    color: var(--text-muted);
    font-family: var(--font-mono);
}

.code-body {
    padding: 1.5rem;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    line-height: 1.8;
    overflow-x: auto;
}

.code-body code {
    font-family: inherit;
}

.code-keyword { color: #c678dd; }
.code-class { color: #e5c07b; }
.code-func { color: #61afef; }
.code-string { color: #98c379; }

/* ===== Skills Section ===== */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 1.5rem;
}

.skill-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 2rem;
    transition: all var(--transition);
    box-shadow: var(--card-shadow);
}

.skill-card:hover {
    transform: translateY(-4px);
    border-color: var(--accent);
    box-shadow: var(--card-shadow-hover);
    background: var(--bg-card-hover);
}

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

.skill-card h3 {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.skill-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1.25rem;
}

.skill-bar {
    height: 4px;
    background: var(--border);
    border-radius: 2px;
    overflow: hidden;
}

.skill-fill {
    height: 100%;
    width: 0;
    background: var(--accent-gradient);
    border-radius: 2px;
    transition: width 1.5s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ===== Projects Section ===== */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 1.5rem;
}

.project-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 2rem;
    transition: all var(--transition);
    display: flex;
    flex-direction: column;
    box-shadow: var(--card-shadow);
}

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

.project-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.25rem;
}

.project-icon {
    font-size: 2rem;
}

.project-links a {
    color: var(--text-muted);
    transition: color var(--transition);
}

.project-links a:hover {
    color: var(--accent-light);
}

.project-date {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--accent-light);
    background: var(--accent-bg);
    padding: 0.15rem 0.6rem;
    border-radius: 50px;
    margin-bottom: 0.5rem;
    font-family: var(--font-mono);
}

.project-title {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.project-desc {
    color: var(--text-secondary);
    font-size: 0.9rem;
    flex-grow: 1;
    margin-bottom: 1.25rem;
}

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

.tag {
    font-size: 0.75rem;
    padding: 0.25rem 0.75rem;
    background: var(--accent-bg);
    color: var(--accent-light);
    border-radius: 50px;
    font-family: var(--font-mono);
}

/* ===== Timeline / Experience ===== */
.timeline {
    position: relative;
    max-width: 700px;
    margin: 0 auto;
    padding-left: 2rem;
}

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

.timeline-item {
    position: relative;
    padding-bottom: 2.5rem;
}

.timeline-item:last-child {
    padding-bottom: 0;
}

.timeline-dot {
    position: absolute;
    left: -2rem;
    top: 0.5rem;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--accent);
    border: 3px solid var(--bg-secondary);
    transform: translateX(-5px);
    box-shadow: 0 0 10px var(--accent-glow);
}

.timeline-content {
    padding-left: 1rem;
}

.timeline-date {
    display: inline-block;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--accent-light);
    background: var(--accent-bg);
    padding: 0.2rem 0.75rem;
    border-radius: 50px;
    margin-bottom: 0.5rem;
    font-family: var(--font-mono);
}

.timeline-content h3 {
    font-size: 1.15rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

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

/* ===== Publications Section ===== */
.publications-list {
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.pub-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.75rem;
    transition: all var(--transition);
    box-shadow: var(--card-shadow);
}

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

.pub-venue {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--accent-light);
    background: rgba(99, 102, 241, 0.15);
    padding: 0.2rem 0.75rem;
    border-radius: 50px;
    margin-bottom: 0.75rem;
    font-family: var(--font-mono);
    letter-spacing: 0.02em;
}

.pub-title {
    font-size: 1.05rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    line-height: 1.5;
}

.pub-authors {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.pub-detail {
    font-size: 0.85rem;
    color: var(--text-muted);
    line-height: 1.6;
}

.pub-link {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    margin-top: 0.75rem;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--accent-light);
    padding: 0.3rem 0.8rem;
    border: 1px solid var(--border);
    border-radius: 50px;
    transition: all var(--transition);
}

.pub-link:hover {
    border-color: var(--accent);
    background: var(--accent-bg);
    color: var(--accent-light);
}

/* ===== Contact Section ===== */
.contact-content {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

.contact-desc {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: 2rem;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--text-secondary);
    padding: 1rem 2rem;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    transition: all var(--transition);
}

.contact-item:hover {
    border-color: var(--accent);
    color: var(--accent-light);
    background: rgba(99, 102, 241, 0.05);
    transform: translateY(-2px);
}

.contact-item svg {
    flex-shrink: 0;
}

/* ===== Footer ===== */
.footer {
    padding: 2rem;
    text-align: center;
    border-top: 1px solid var(--border);
    color: var(--text-muted);
    font-size: 0.85rem;
}

.visitor-count {
    margin-top: 0.5rem;
}

/* ===== Scroll Reveal Animation ===== */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s ease, transform 0.8s ease;
}

.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: 70px;
        left: 0;
        right: 0;
        background: var(--nav-bg-scroll);
        backdrop-filter: blur(20px);
        flex-direction: column;
        align-items: center;
        padding: 2rem;
        gap: 1.5rem;
        border-bottom: 1px solid var(--border);
    }

    .nav-links.active {
        display: flex;
    }

    .nav-toggle {
        display: flex;
    }

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

    .about-stats {
        justify-content: center;
    }

    .hero-cta {
        flex-direction: column;
        align-items: center;
    }

    .contact-links {
        flex-direction: column;
        align-items: center;
    }

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

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

    .section {
        padding: 4rem 1.5rem;
    }
}

/* ===== Light Mode Overrides ===== */
[data-theme="light"] .particle {
    background: var(--accent-light);
    opacity: 0.3;
}

[data-theme="light"] .hero {
    background: linear-gradient(135deg, #f0f0ff 0%, #e8e8f8 50%, #f8f9fa 100%);
}

[data-theme="light"] .hero-greeting,
[data-theme="light"] .hero-title-static,
[data-theme="light"] .hero-title-dynamic,
[data-theme="light"] .cursor {
    color: var(--text-primary);
}

[data-theme="light"] .code-body {
    background: #f6f6fa;
    color: var(--text-primary);
}

[data-theme="light"] .code-keyword { color: #7c3aed; }
[data-theme="light"] .code-string { color: #059669; }
[data-theme="light"] .code-class { color: #d97706; }
[data-theme="light"] .code-func { color: #2563eb; }

[data-theme="light"] .section-alt {
    background: #f0f0f5;
}

[data-theme="light"] .btn-outline:hover {
    background: var(--accent);
    border-color: var(--accent);
    color: #fff;
}

[data-theme="light"] .footer {
    background: #f0f0f5;
}