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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   DESIGN TOKENS
   ============================================ */
:root {
    --bg:        #06091a;
    --bg-2:      #0a0f22;
    --card:      #0e1929;
    --border:    #1a2d45;
    --blue:      #38bdf8;
    --indigo:    #818cf8;
    --green:     #34d399;
    --amber:     #fbbf24;
    --orange:    #fb923c;
    --gradient:  linear-gradient(135deg, #38bdf8 0%, #818cf8 100%);
    --text:      #dde6f0;
    --muted:     #6e8fa8;
    --dim:       #2d4460;
    --radius:    14px;
    --radius-sm: 8px;
    --transition: 0.2s ease;
    --max-w:     1100px;
    --pad-x:     24px;
    --section-y: 100px;
}

/* ============================================
   UTILITIES
   ============================================ */
.container {
    max-width: var(--max-w);
    margin: 0 auto;
    padding: 0 var(--pad-x);
}

a { color: inherit; }

/* ============================================
   BUTTONS
   ============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 13px 26px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.9rem;
    text-decoration: none;
    transition: var(--transition);
    cursor: pointer;
    border: none;
    white-space: nowrap;
    font-family: inherit;
}

.btn-primary {
    background: var(--gradient);
    color: #fff;
}
.btn-primary:hover {
    opacity: 0.85;
    transform: translateY(-2px);
}

.btn-sm {
    padding: 8px 18px;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--blue);
    border: 1.5px solid var(--blue);
    border-radius: var(--radius-sm);
    text-decoration: none;
    transition: var(--transition);
    background: transparent;
}
.btn-sm:hover {
    background: rgba(56, 189, 248, 0.1);
}

.link {
    color: var(--blue);
    text-decoration: none;
    transition: var(--transition);
}
.link:hover { opacity: 0.75; }

/* ============================================
   ANIMATIONS
   ============================================ */
.fade-in {
    animation: fadeUp 0.9s cubic-bezier(0.22, 1, 0.36, 1) both;
}

@keyframes fadeUp {
    from { opacity: 0; transform: translateY(28px); }
    to   { opacity: 1; transform: translateY(0); }
}

.reveal {
    opacity: 0;
    transform: translateY(24px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ============================================
   NAVIGATION
   ============================================ */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    padding: 18px 0;
    transition: background 0.3s ease, border-bottom 0.3s ease, padding 0.3s ease;
}
.nav.scrolled {
    background: rgba(6, 9, 26, 0.92);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--border);
    padding: 12px 0;
}

.nav__container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
}

.nav__logo {
    font-size: 1.2rem;
    font-weight: 800;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-decoration: none;
    letter-spacing: -0.5px;
    flex-shrink: 0;
}

.nav__menu {
    display: flex;
    align-items: center;
    gap: 4px;
    list-style: none;
}

.nav__link {
    color: var(--muted);
    text-decoration: none;
    font-size: 0.88rem;
    font-weight: 500;
    padding: 6px 12px;
    border-radius: 6px;
    transition: var(--transition);
}
.nav__link:hover,
.nav__link.active {
    color: var(--text);
    background: rgba(255, 255, 255, 0.05);
}

.nav__toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}
.nav__toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--text);
    border-radius: 2px;
    transition: transform 0.25s ease, opacity 0.25s ease;
}
.nav__toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav__toggle.open span:nth-child(2) { opacity: 0; }
.nav__toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ============================================
   HERO
   ============================================ */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    overflow: hidden;
}

.hero__bg {
    position: absolute;
    inset: 0;
    background: var(--bg);
    overflow: hidden;
}

.hero__glow {
    position: absolute;
    border-radius: 50%;
    filter: blur(90px);
    opacity: 0.13;
    pointer-events: none;
}
.hero__glow--1 {
    width: 700px;
    height: 700px;
    background: #38bdf8;
    top: -250px;
    right: -150px;
}
.hero__glow--2 {
    width: 550px;
    height: 550px;
    background: #818cf8;
    bottom: -150px;
    left: -150px;
}

.hero__container {
    position: relative;
    z-index: 1;
    padding-top: 90px;
    padding-bottom: 60px;
}

.hero__content {
    max-width: 680px;
}

.hero__greeting {
    font-size: 1rem;
    color: var(--blue);
    font-weight: 500;
    margin-bottom: 10px;
    letter-spacing: 0.03em;
}

.hero__name {
    font-size: clamp(3rem, 7vw, 5.5rem);
    font-weight: 800;
    line-height: 1.0;
    letter-spacing: -2.5px;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 14px;
}

.hero__title {
    font-size: clamp(1.05rem, 2.5vw, 1.3rem);
    color: var(--text);
    font-weight: 500;
    margin-bottom: 20px;
    opacity: 0.8;
}

.hero__bio {
    font-size: 1.05rem;
    color: var(--muted);
    max-width: 580px;
    line-height: 1.8;
    margin-bottom: 36px;
}

.hero__social {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 28px;
}

.social-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 18px;
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    text-decoration: none;
    font-size: 0.88rem;
    font-weight: 500;
    transition: var(--transition);
}
.social-link:hover {
    background: rgba(56, 189, 248, 0.08);
    border-color: rgba(56, 189, 248, 0.4);
    color: var(--blue);
    transform: translateY(-2px);
}

.hero__scroll-indicator {
    position: absolute;
    bottom: 36px;
    left: 50%;
    transform: translateX(-50%);
    width: 1px;
    height: 56px;
    background: linear-gradient(to bottom, rgba(56, 189, 248, 0.6), transparent);
    animation: pulse 2.5s ease-in-out infinite;
}
@keyframes pulse {
    0%, 100% { opacity: 0.3; }
    50%       { opacity: 1; }
}

/* ============================================
   SECTIONS — SHARED
   ============================================ */
.section {
    padding: var(--section-y) 0;
}
.section--alt {
    background: var(--bg-2);
}

.section-header {
    margin-bottom: 56px;
    text-align: center;
}
.section-label {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--blue);
    margin-bottom: 10px;
}
.section-title {
    font-size: clamp(1.9rem, 4vw, 2.9rem);
    font-weight: 800;
    letter-spacing: -1.5px;
    color: var(--text);
    line-height: 1.1;
}
.section-subtitle {
    margin-top: 14px;
    font-size: 0.93rem;
    color: var(--muted);
}

/* ============================================
   ABOUT
   ============================================ */
.about__grid {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 64px;
    align-items: start;
}

.about__stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
    min-width: 270px;
}

.stat-card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 22px 16px;
    text-align: center;
}
.stat-card__value {
    display: block;
    font-size: 1.9rem;
    font-weight: 800;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1.1;
    margin-bottom: 5px;
}
.stat-card__label {
    font-size: 0.76rem;
    color: var(--muted);
    font-weight: 500;
    line-height: 1.4;
}

.about__bio p {
    color: var(--muted);
    margin-bottom: 18px;
    font-size: 1.02rem;
    line-height: 1.85;
}
.about__bio p:last-child { margin-bottom: 0; }
.about__bio strong { color: var(--text); font-weight: 600; }

/* ============================================
   SKILLS
   ============================================ */
.skills__grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 18px;
}

.skill-card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    transition: border-color var(--transition), transform var(--transition);
}
.skill-card:hover {
    border-color: rgba(56, 189, 248, 0.3);
    transform: translateY(-3px);
}

.skill-card__title {
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 16px;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--border);
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 7px;
}
.skill-tag {
    font-size: 0.76rem;
    font-weight: 500;
    color: var(--muted);
    background: rgba(56, 189, 248, 0.05);
    border: 1px solid rgba(56, 189, 248, 0.12);
    border-radius: 4px;
    padding: 4px 10px;
    line-height: 1.4;
}

/* ============================================
   EXPERIENCE / TIMELINE
   ============================================ */
.timeline {
    position: relative;
    padding-left: 32px;
}
.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 6px;
    bottom: 40px;
    width: 2px;
    background: linear-gradient(to bottom, var(--blue), var(--indigo), transparent);
    border-radius: 2px;
}

.timeline-item {
    position: relative;
    margin-bottom: 56px;
}
.timeline-item:last-child { margin-bottom: 0; }

.timeline-item::before {
    content: '';
    position: absolute;
    left: -38px;
    top: 5px;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--blue);
    border: 2.5px solid var(--bg);
    box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.2);
}

.timeline-item__header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 16px;
    margin-bottom: 16px;
    flex-wrap: wrap;
}
.timeline-item__role {
    font-size: 1.08rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 4px;
}
.timeline-item__company {
    font-size: 0.88rem;
    color: var(--blue);
    font-weight: 500;
}
.timeline-item__date {
    font-size: 0.8rem;
    color: var(--muted);
    font-weight: 500;
    white-space: nowrap;
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 4px 12px;
    flex-shrink: 0;
    margin-top: 2px;
}

.timeline-item__points {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 10px;
}
.timeline-item__points li {
    font-size: 0.92rem;
    color: var(--muted);
    line-height: 1.75;
    padding-left: 18px;
    position: relative;
}
.timeline-item__points li::before {
    content: '▸';
    position: absolute;
    left: 0;
    color: var(--blue);
    font-size: 0.72rem;
    top: 4px;
}
.timeline-item__points strong { color: var(--text); }

/* ============================================
   PUBLICATIONS
   ============================================ */
.pub-year {
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--blue);
    padding: 28px 0 14px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 4px;
}
.pub-year:first-child { padding-top: 0; }

.pub-card {
    border-bottom: 1px solid rgba(26, 45, 69, 0.6);
    padding: 20px 0;
    transition: padding-left var(--transition);
}
.pub-card:hover { padding-left: 10px; }
.pub-card--preprint { opacity: 0.6; }

.pub-card__header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 16px;
    margin-bottom: 8px;
    flex-wrap: wrap;
}
.pub-card__title {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text);
    line-height: 1.55;
    flex: 1;
    min-width: 200px;
}
.pub-card__badges {
    display: flex;
    gap: 6px;
    flex-wrap: wrap;
    flex-shrink: 0;
    margin-top: 2px;
}
.pub-card__authors {
    font-size: 0.83rem;
    color: var(--muted);
    line-height: 1.6;
}
.pub-card__authors strong {
    color: var(--blue);
    font-weight: 600;
}

.badge {
    font-size: 0.7rem;
    font-weight: 700;
    padding: 3px 9px;
    border-radius: 4px;
    white-space: nowrap;
    line-height: 1.5;
}
.badge--acl {
    background: rgba(56, 189, 248, 0.1);
    color: var(--blue);
    border: 1px solid rgba(56, 189, 248, 0.2);
}
.badge--ieee {
    background: rgba(52, 211, 153, 0.1);
    color: var(--green);
    border: 1px solid rgba(52, 211, 153, 0.2);
}
.badge--springer {
    background: rgba(251, 146, 60, 0.1);
    color: var(--orange);
    border: 1px solid rgba(251, 146, 60, 0.2);
}
.badge--journal {
    background: rgba(129, 140, 248, 0.1);
    color: var(--indigo);
    border: 1px solid rgba(129, 140, 248, 0.2);
}
.badge--award {
    background: rgba(251, 191, 36, 0.1);
    color: var(--amber);
    border: 1px solid rgba(251, 191, 36, 0.2);
}
.badge--preprint {
    background: rgba(100, 116, 139, 0.1);
    color: #64748b;
    border: 1px solid rgba(100, 116, 139, 0.2);
}

.pub-note {
    font-size: 0.78rem;
    color: var(--dim);
    margin-top: 28px;
    font-style: italic;
}

/* ============================================
   EDUCATION
   ============================================ */
.edu-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
}

.edu-card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    transition: border-color var(--transition), transform var(--transition);
}
.edu-card:hover {
    border-color: rgba(56, 189, 248, 0.3);
    transform: translateY(-2px);
}
.edu-card__degree {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 8px;
}
.edu-card__school {
    font-size: 0.87rem;
    color: var(--blue);
    font-weight: 500;
    margin-bottom: 8px;
}
.edu-card__date {
    font-size: 0.8rem;
    color: var(--muted);
    margin-bottom: 12px;
}
.edu-card__detail {
    font-size: 0.87rem;
    color: var(--muted);
    line-height: 1.75;
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
    background: var(--bg-2);
    border-top: 1px solid var(--border);
    padding: 52px 0;
    text-align: center;
}
.footer__name {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 6px;
}
.footer__tagline {
    font-size: 0.86rem;
    color: var(--muted);
    margin-bottom: 24px;
}
.footer__links {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 28px;
    margin-bottom: 28px;
}
.footer__links a {
    font-size: 0.86rem;
    color: var(--muted);
    text-decoration: none;
    transition: color var(--transition);
}
.footer__links a:hover { color: var(--blue); }
.footer__copy {
    font-size: 0.76rem;
    color: var(--dim);
}

/* ============================================
   RESPONSIVE — TABLET (≤1024px)
   ============================================ */
@media (max-width: 1024px) {
    .skills__grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* ============================================
   RESPONSIVE — MOBILE (≤768px)
   ============================================ */
@media (max-width: 768px) {
    :root {
        --section-y: 64px;
        --pad-x: 20px;
    }

    /* Nav */
    .nav__toggle { display: flex; }

    .nav__menu {
        display: none;
        position: fixed;
        inset: 0;
        top: 60px;
        background: rgba(6, 9, 26, 0.97);
        backdrop-filter: blur(16px);
        -webkit-backdrop-filter: blur(16px);
        flex-direction: column;
        align-items: center;
        justify-content: center;
        gap: 24px;
    }
    .nav__menu.open { display: flex; }
    .nav__link { font-size: 1.15rem; padding: 8px 20px; }

    /* Hero */
    .hero__name { letter-spacing: -1.5px; }
    .hero__social { gap: 8px; }
    .social-link { font-size: 0.82rem; padding: 8px 14px; }

    /* About */
    .about__grid {
        grid-template-columns: 1fr;
        gap: 36px;
    }
    .about__stats { min-width: unset; }

    /* Skills */
    .skills__grid { grid-template-columns: 1fr; }

    /* Timeline */
    .timeline-item__header { flex-direction: column; gap: 8px; }

    /* Education */
    .edu-grid { grid-template-columns: 1fr; }

    /* Publications */
    .pub-card__header { flex-direction: column; gap: 10px; }
    .pub-card__title { min-width: unset; }
}

@media (max-width: 480px) {
    .hero__scroll-indicator { display: none; }
    .about__stats { grid-template-columns: 1fr 1fr; }
}