/* ===== Design tokens ===== */
:root,
[data-theme='light'] {
  --color-bg: #f4f6f9;
  --color-surface: #ffffff;
  --color-surface-2: #eef1f6;
  --color-surface-offset: #e7ebf1;
  --color-surface-offset-2: #dde3ec;
  --color-divider: #e2e6ec;
  --color-border: #d7dce4;

  --color-text: #10151f;
  --color-text-muted: #57606f;
  --color-text-faint: #97a0ad;
  --color-text-inverse: #f4f6f9;

  --color-primary: #0891b2;
  --color-primary-hover: #0e7490;
  --color-primary-active: #155e75;
  --color-primary-highlight: #cffafe;

  --color-gold: #b07a00;
  --color-success: #2e7d32;

  --radius-sm: 0.375rem;
  --radius-md: 0.625rem;
  --radius-lg: 1rem;
  --radius-xl: 1.5rem;
  --radius-full: 9999px;

  --transition-interactive: 180ms cubic-bezier(0.16, 1, 0.3, 1);

  --shadow-sm: 0 1px 2px rgba(10, 20, 30, 0.06);
  --shadow-md: 0 8px 24px rgba(10, 20, 30, 0.08);
  --shadow-lg: 0 20px 48px rgba(10, 20, 30, 0.14);

  --content-wide: 1180px;
  --content-default: 860px;

  --font-display: 'Cabinet Grotesk', 'General Sans', 'Segoe UI', sans-serif;
  --font-body: 'Satoshi', 'Inter', 'Segoe UI', sans-serif;
}

[data-theme='dark'] {
  --color-bg: #0a0e14;
  --color-surface: #10161f;
  --color-surface-2: #141b26;
  --color-surface-offset: #1a222f;
  --color-surface-offset-2: #202b3a;
  --color-divider: #1c2430;
  --color-border: #232c3a;

  --color-text: #e7eaf0;
  --color-text-muted: #93a0b4;
  --color-text-faint: #5c6b81;
  --color-text-inverse: #0a0e14;

  --color-primary: #22d3ee;
  --color-primary-hover: #67e8f9;
  --color-primary-active: #a5f3fc;
  --color-primary-highlight: #113947;

  --color-gold: #e8af34;
  --color-success: #6daa45;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.35);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 20px 48px rgba(0, 0, 0, 0.55);
}

/* Type scale */
:root {
  --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm: clamp(0.875rem, 0.8rem + 0.35vw, 1rem);
  --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
  --text-lg: clamp(1.125rem, 1rem + 0.75vw, 1.5rem);
  --text-xl: clamp(1.5rem, 1.2rem + 1.25vw, 2.25rem);
  --text-2xl: clamp(2rem, 1.2rem + 2.5vw, 3.25rem);
  --text-hero: clamp(2.75rem, 1rem + 6vw, 6.5rem);

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  --space-32: 8rem;
}

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

html {
  -webkit-text-size-adjust: none;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  scroll-padding-top: 88px;
}

body {
  min-height: 100dvh;
  line-height: 1.6;
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  transition: background-color var(--transition-interactive), color var(--transition-interactive);
}

img, picture, video, canvas, svg { display: block; max-width: 100%; height: auto; }
ul[role='list'], ol[role='list'] { list-style: none; }
input, button, textarea, select { font: inherit; color: inherit; }

h1, h2, h3, h4 { text-wrap: balance; line-height: 1.15; font-family: var(--font-display); }
p, li, figcaption { text-wrap: pretty; max-width: 72ch; }

::selection { background: color-mix(in oklab, var(--color-primary) 30%, transparent); color: var(--color-text); }
:focus-visible { outline: 2px solid var(--color-primary); outline-offset: 3px; border-radius: var(--radius-sm); }

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

button { cursor: pointer; background: none; border: none; }

a, button, [role='button'] {
  transition: color var(--transition-interactive), background var(--transition-interactive),
    border-color var(--transition-interactive), box-shadow var(--transition-interactive), transform var(--transition-interactive);
}

.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; }

.skip-link {
  position: absolute; left: -9999px; top: 0; background: var(--color-primary); color: #fff;
  padding: var(--space-2) var(--space-4); z-index: 200; border-radius: var(--radius-sm);
}
.skip-link:focus { left: var(--space-4); top: var(--space-4); }

.container { max-width: var(--content-wide); margin-inline: auto; padding-inline: clamp(var(--space-5), 5vw, var(--space-12)); }

.section { padding-block: clamp(var(--space-16), 9vw, var(--space-32)); position: relative; }
.section-label {
  font-size: var(--text-xs); text-transform: uppercase; letter-spacing: 0.14em;
  color: var(--color-primary); font-weight: 600; margin-bottom: var(--space-3);
}
.section-title { font-size: var(--text-2xl); font-weight: 700; margin-bottom: var(--space-6); letter-spacing: -0.01em; }

/* ===== Reveal animation ===== */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity 0.7s cubic-bezier(0.16,1,0.3,1), transform 0.7s cubic-bezier(0.16,1,0.3,1); }
.reveal.is-visible { opacity: 1; transform: translateY(0); }

/* ===== Buttons ===== */
.btn {
  display: inline-flex; align-items: center; gap: var(--space-2);
  font-size: var(--text-sm); font-weight: 600; padding: 0.75rem 1.4rem;
  border-radius: var(--radius-full); text-decoration: none; white-space: nowrap;
}
.btn-primary { background: var(--color-primary); color: #04141a; }
.btn-primary:hover { background: var(--color-primary-hover); transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn-ghost { background: transparent; color: var(--color-text); border: 1px solid var(--color-border); }
.btn-ghost:hover { border-color: var(--color-primary); color: var(--color-primary); }
.btn-ghost.is-active { background: var(--color-primary); color: #04141a; border-color: var(--color-primary); }
.btn-text { background: none; color: var(--color-text-muted); padding: 0.5rem 0; }
.btn-text:hover { color: var(--color-primary); }

/* ===== Header ===== */
.header {
  position: sticky; top: 0; z-index: 100;
  background: color-mix(in oklab, var(--color-bg) 88%, transparent);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--color-divider);
  transition: transform 0.3s cubic-bezier(0.16,1,0.3,1), box-shadow 0.3s cubic-bezier(0.16,1,0.3,1);
}
.header--hidden { transform: translateY(-100%); }
.header--scrolled { box-shadow: var(--shadow-sm); }

.header-inner {
  max-width: var(--content-wide); margin-inline: auto;
  padding: var(--space-4) clamp(var(--space-5), 5vw, var(--space-12));
  display: flex; align-items: center; justify-content: space-between; gap: var(--space-6);
}
.logo { display: flex; align-items: center; gap: var(--space-2); color: var(--color-text); text-decoration: none; }
.logo svg { color: var(--color-primary); flex-shrink: 0; }
.logo-mark { width: 38px; height: 34px; object-fit: contain; flex-shrink: 0; }
.logo-text { font-family: var(--font-display); font-weight: 600; font-size: var(--text-base); }

.nav { display: flex; gap: var(--space-8); }
.nav a { color: var(--color-text-muted); text-decoration: none; font-size: var(--text-sm); font-weight: 500; }
.nav a:hover { color: var(--color-primary); }

.header-actions { display: flex; align-items: center; gap: var(--space-2); }
.theme-toggle, .nav-toggle {
  display: flex; align-items: center; justify-content: center;
  width: 40px; height: 40px; border-radius: var(--radius-full);
  color: var(--color-text); border: 1px solid var(--color-border);
}
.theme-toggle:hover, .nav-toggle:hover { border-color: var(--color-primary); color: var(--color-primary); }
.nav-toggle { display: none; }

.nav-mobile {
  display: none; flex-direction: column; padding: var(--space-4) clamp(var(--space-5), 5vw, var(--space-12));
  border-top: 1px solid var(--color-divider);
}
.nav-mobile a { padding: var(--space-3) 0; color: var(--color-text); text-decoration: none; font-size: var(--text-base); border-bottom: 1px solid var(--color-divider); }
.nav-mobile.is-open { display: flex; }

@media (max-width: 860px) {
  .nav { display: none; }
  .nav-toggle { display: flex; }
}

/* ===== Hero ===== */
.hero {
  position: relative; min-height: 92vh; display: flex; align-items: center;
  overflow: hidden; padding-block: var(--space-20);
}
#network-canvas { position: absolute; inset: 0; width: 100%; height: 100%; z-index: 0; opacity: 0.55; }
.hero-inner {
  position: relative; z-index: 1; max-width: var(--content-wide); margin-inline: auto;
  padding-inline: clamp(var(--space-5), 5vw, var(--space-12)); width: 100%;
}
.eyebrow {
  font-size: var(--text-sm); color: var(--color-primary); font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.12em; margin-bottom: var(--space-5);
}
.hero-title { font-size: var(--text-hero); font-weight: 700; letter-spacing: -0.02em; margin-bottom: var(--space-6); }
.hero-sub { font-size: var(--text-lg); color: var(--color-text-muted); max-width: 46ch; margin-bottom: var(--space-8); }
.hero-actions { display: flex; align-items: center; gap: var(--space-4); flex-wrap: wrap; margin-bottom: var(--space-16); }
.hero-actions .btn-text svg { transform: translateY(1px); }

.hero-stats { display: grid; grid-template-columns: repeat(4, minmax(0,1fr)); gap: var(--space-6); max-width: 720px; }
.hero-stats div { border-top: 1px solid var(--color-border); padding-top: var(--space-3); }
.hero-stats dt { font-family: var(--font-display); font-size: var(--text-lg); font-weight: 700; color: var(--color-primary); }
.hero-stats dd { font-size: var(--text-xs); color: var(--color-text-muted); margin-top: var(--space-1); }

@media (max-width: 640px) {
  .hero-stats { grid-template-columns: repeat(2, minmax(0,1fr)); }
  .hero-title { font-size: clamp(2.5rem, 12vw, 4rem); }
}

.scroll-cue { position: absolute; bottom: var(--space-8); left: 50%; transform: translateX(-50%); z-index: 1; }
.scroll-cue span {
  display: block; width: 1px; height: 34px; background: linear-gradient(var(--color-primary), transparent);
  animation: scrollcue 1.8s ease-in-out infinite;
}
@keyframes scrollcue { 0%,100% { opacity: 0.2; } 50% { opacity: 1; } }

/* ===== About ===== */
.about-grid { display: grid; grid-template-columns: 320px 1fr; gap: clamp(var(--space-10), 6vw, var(--space-20)); align-items: start; }
.about-photo-frame {
  border-radius: var(--radius-lg); overflow: hidden; border: 1px solid var(--color-border);
  box-shadow: var(--shadow-md); aspect-ratio: 7/8;
}
.about-photo-frame img { width: 100%; height: 100%; object-fit: cover; }
.chip-list { display: flex; flex-wrap: wrap; gap: var(--space-2); margin-top: var(--space-5); }
.chip-list li {
  font-size: var(--text-xs); font-weight: 600; padding: 0.4rem 0.85rem; border-radius: var(--radius-full);
  background: var(--color-surface-2); border: 1px solid var(--color-border); color: var(--color-text-muted);
}
.about-copy p { color: var(--color-text-muted); margin-bottom: var(--space-5); }
.about-copy p strong { color: var(--color-text); font-weight: 700; }
.signature { margin-top: var(--space-8); width: 160px; opacity: 0.85; }
.signature img { filter: none; }
[data-theme='dark'] .signature img { filter: invert(1); }

@media (max-width: 780px) {
  .about-grid { grid-template-columns: 1fr; }
  .about-photo-frame { max-width: 260px; }
}

/* ===== Experience timeline ===== */
.timeline { position: relative; display: flex; flex-direction: column; gap: var(--space-10); padding-left: var(--space-8); border-left: 1px solid var(--color-border); }
.timeline-item { position: relative; }
.timeline-marker {
  position: absolute; left: calc(-1 * var(--space-8) - 5px); top: 0.4rem;
  width: 11px; height: 11px; border-radius: 50%; background: var(--color-bg);
  border: 2px solid var(--color-primary);
}
.timeline-card { background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius-lg); padding: var(--space-6); box-shadow: var(--shadow-sm); }
.timeline-head { display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: var(--space-2); margin-bottom: var(--space-1); }
.timeline-head h3 { font-size: var(--text-lg); font-weight: 700; }
.timeline-date { font-size: var(--text-xs); color: var(--color-text-faint); white-space: nowrap; }
.timeline-org { font-size: var(--text-sm); color: var(--color-primary); font-weight: 600; margin-bottom: var(--space-3); }
.timeline-card p:last-child { color: var(--color-text-muted); font-size: var(--text-sm); }

/* ===== Education ===== */
.edu-grid { display: grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap: var(--space-5); margin-bottom: var(--space-10); }
.edu-card { position: relative; background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius-lg); padding: var(--space-6); box-shadow: var(--shadow-sm); }
.edu-card h3 { font-size: var(--text-base); font-weight: 700; margin-bottom: var(--space-2); }
.edu-major, .edu-school { font-size: var(--text-sm); color: var(--color-text-muted); }
.edu-date { font-size: var(--text-xs); color: var(--color-text-faint); margin-top: var(--space-2); }
.edu-tag {
  position: absolute; top: var(--space-5); right: var(--space-5);
  font-size: var(--text-xs); font-weight: 600; color: var(--color-primary);
  background: var(--color-primary-highlight); padding: 0.25rem 0.65rem; border-radius: var(--radius-full);
}
@media (max-width: 700px) { .edu-grid { grid-template-columns: 1fr; } }

.cert-row {
  display: flex; gap: var(--space-5); align-items: flex-start; background: var(--color-surface-2);
  border: 1px solid var(--color-border); border-radius: var(--radius-lg); padding: var(--space-6);
}
.cert-icon { flex-shrink: 0; width: 42px; height: 42px; border-radius: var(--radius-md); background: var(--color-primary-highlight); color: var(--color-primary); display: flex; align-items: center; justify-content: center; }
.cert-row h3 { font-size: var(--text-base); font-weight: 700; margin-bottom: var(--space-2); }
.cert-row p { font-size: var(--text-sm); color: var(--color-text-muted); }

/* ===== Research / publications ===== */
.research-intro { color: var(--color-text-muted); max-width: 68ch; margin-bottom: var(--space-8); font-size: var(--text-base); }
.pub-filters { display: flex; gap: var(--space-2); flex-wrap: wrap; margin-bottom: var(--space-8); }
.pub-filter {
  font-size: var(--text-xs); font-weight: 600; padding: 0.5rem 1rem; border-radius: var(--radius-full);
  border: 1px solid var(--color-border); color: var(--color-text-muted); background: transparent;
}
.pub-filter:hover { border-color: var(--color-primary); color: var(--color-primary); }
.pub-filter.is-active { background: var(--color-primary); color: #04141a; border-color: var(--color-primary); }

.pub-list { display: flex; flex-direction: column; gap: var(--space-3); }
.pub-item {
  display: grid; grid-template-columns: 64px 1fr; gap: var(--space-5);
  padding: var(--space-5); border: 1px solid var(--color-border); border-radius: var(--radius-lg);
  background: var(--color-surface); transition: border-color var(--transition-interactive), box-shadow var(--transition-interactive);
}
.pub-item:hover { border-color: var(--color-primary); box-shadow: var(--shadow-sm); }
.pub-year { font-family: var(--font-display); font-size: var(--text-lg); font-weight: 700; color: var(--color-primary); }
.pub-body h3 { font-size: var(--text-base); font-weight: 700; margin-bottom: var(--space-2); line-height: 1.35; }
.pub-body .pub-meta { font-size: var(--text-xs); color: var(--color-text-faint); margin-bottom: var(--space-2); }
.pub-body a { font-size: var(--text-sm); color: var(--color-primary); text-decoration: none; font-weight: 600; }
.pub-body a:hover { text-decoration: underline; }
.pub-item[hidden] { display: none; }
.pub-item.is-collapsed { display: none; }

.pub-toggle { margin-top: var(--space-8); }

@media (max-width: 600px) {
  .pub-item { grid-template-columns: 1fr; gap: var(--space-2); }
}

/* ===== Awards ===== */
.award-card {
  display: grid; grid-template-columns: 48px 1fr; gap: var(--space-5); align-items: flex-start;
  background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius-lg);
  padding: var(--space-6); margin-bottom: var(--space-10); box-shadow: var(--shadow-sm);
}
.award-icon { width: 48px; height: 48px; border-radius: var(--radius-md); background: var(--color-primary-highlight); color: var(--color-primary); display: flex; align-items: center; justify-content: center; }
.award-card h3 { font-size: var(--text-base); font-weight: 700; margin-bottom: var(--space-2); }
.award-card p { font-size: var(--text-sm); color: var(--color-text-muted); }
.award-card a { color: var(--color-primary); font-weight: 600; text-decoration: none; }
.award-card a:hover { text-decoration: underline; }

.membership-list { display: grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap: var(--space-4); }
.membership-item { border-left: 2px solid var(--color-primary); padding-left: var(--space-4); }
.membership-item h4 { font-size: var(--text-sm); font-weight: 700; margin-bottom: var(--space-1); }
.membership-item p { font-size: var(--text-sm); color: var(--color-text-muted); }
.membership-item a { color: var(--color-primary); text-decoration: none; font-weight: 600; }
.membership-item a:hover { text-decoration: underline; }
@media (max-width: 700px) { .membership-list { grid-template-columns: 1fr; } }

/* ===== Contact ===== */
.contact { background: var(--color-surface-2); border-top: 1px solid var(--color-divider); }
.contact-grid { display: grid; grid-template-columns: 1.1fr 1fr; gap: clamp(var(--space-10), 6vw, var(--space-20)); align-items: center; }
.contact-grid > div:first-child p { color: var(--color-text-muted); margin-top: var(--space-4); }
.contact-links { display: flex; flex-direction: column; gap: var(--space-3); }
.contact-link {
  display: flex; align-items: center; gap: var(--space-3); padding: var(--space-4) var(--space-5);
  background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius-lg);
  color: var(--color-text); text-decoration: none; font-size: var(--text-sm); font-weight: 600;
}
.contact-link svg { color: var(--color-primary); flex-shrink: 0; }
.contact-link:hover { border-color: var(--color-primary); transform: translateX(4px); }
.contact-location { font-size: var(--text-xs); color: var(--color-text-faint); text-align: center; margin-top: var(--space-2); }

@media (max-width: 780px) { .contact-grid { grid-template-columns: 1fr; } }

/* ===== Footer ===== */
.footer { border-top: 1px solid var(--color-divider); padding-block: var(--space-8); }
.footer-inner { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: var(--space-3); font-size: var(--text-xs); color: var(--color-text-faint); }
.footer-inner a { color: var(--color-text-faint); text-decoration: none; }
.footer-inner a:hover { color: var(--color-primary); }