/* ---------- tokens ---------- */
:root {
  --bg: #f6f3ec;          /* notebook paper */
  --bg-2: #efebe1;
  --ink: #1b1a17;
  --ink-2: #4a463e;
  --muted: #7a7468;
  --line: #d9d2c3;
  --accent: #d9381e;      /* Wolfram-ish red */
  --accent-ink: #b42a14;
  --accent-soft: #f6d9d1;
  --cell: #e3ddcf;        /* cell bracket */
  --ca-on: #1b1a17;
  --ca-off: transparent;
  --gold: #c9a227; --silver: #a8adb3; --bronze: #b0703c;

  --serif: "Fraunces", Georgia, serif;
  --sans: "IBM Plex Sans", system-ui, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, monospace;

  --maxw: 1120px;
  --gutter: clamp(16px, 4vw, 40px);
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #121214; --bg-2: #1a1a1d;
    --ink: #ece8df; --ink-2: #c3beb2; --muted: #8b867b;
    --line: #2c2b2f; --cell: #333238;
    --accent: #ff5a3c; --accent-ink: #ff7a60; --accent-soft: #3a1c16;
    --ca-on: #ece8df;
    color-scheme: dark;
  }
}

/* ---------- base ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 72px; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font: 400 17px/1.6 var(--sans);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img { max-width: 100%; height: auto; display: block; }
a { color: inherit; }
h1, h2, h3 { font-family: var(--serif); font-weight: 500; line-height: 1.15; margin: 0; letter-spacing: -0.01em; }
h3 { font-size: 1.25rem; }
p { margin: 0 0 .8em; }
.mono { font-family: var(--mono); font-size: .78rem; letter-spacing: .02em; }
.muted { color: var(--muted); }
.small { font-size: .9rem; }
.skip { position: absolute; left: -999px; }
.skip:focus { left: 16px; top: 16px; z-index: 99; background: var(--ink); color: var(--bg); padding: 8px 12px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 2px; }
::selection { background: var(--accent); color: #fff; }

/* ---------- top bar ---------- */
.topbar {
  position: sticky; top: 0; z-index: 10;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  padding: 14px var(--gutter);
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; font-family: var(--serif); font-size: 1.05rem; }
.brand svg { width: 28px; height: 16px; fill: var(--accent); }
.topbar nav { display: flex; gap: clamp(10px, 2.4vw, 28px); }
.topbar nav a { text-decoration: none; font-size: .9rem; color: var(--ink-2); position: relative; }
.topbar nav a:hover { color: var(--ink); }
.topbar nav a::after { content: ""; position: absolute; left: 0; right: 100%; bottom: -3px; height: 1px; background: var(--accent); transition: right .25s; }
.topbar nav a:hover::after { right: 0; }
@media (max-width: 640px) {
  .brand span { display: none; }
  .topbar nav a:nth-child(3) { display: none; }
}

/* ---------- layout ---------- */
main > section { max-width: var(--maxw); margin: 0 auto; padding-inline: var(--gutter); }
.section { padding-block: clamp(56px, 9vw, 104px); border-top: 1px solid var(--line); }
.section-head { display: flex; align-items: baseline; gap: 16px; margin-bottom: 36px; }
.section-head h2 { font-size: clamp(1.9rem, 4.4vw, 2.9rem); }
.io { color: var(--accent); white-space: nowrap; }
@media (min-width: 1000px) {
  .section-head { margin-left: -96px; }
  .section-head .io { width: 80px; text-align: right; }
}

/* Mathematica-style cell bracket on the right edge */
.cell { position: relative; }
.cell::after {
  content: ""; position: absolute; top: 4px; bottom: 4px; right: -14px; width: 6px;
  border: 1px solid var(--cell); border-left: 0; transition: border-color .2s;
}
.cell:hover::after { border-color: var(--accent); }
@media (max-width: 700px) { .cell::after { right: -8px; } }

/* ---------- hero ---------- */
.hero {
  display: grid; grid-template-columns: 1.05fr 1fr; gap: clamp(28px, 5vw, 64px);
  align-items: center; min-height: calc(100svh - 64px); padding-block: 48px;
}
.kicker { color: var(--accent); text-transform: uppercase; letter-spacing: .14em; margin-bottom: 18px; }
.hero h1 { font-size: clamp(3.2rem, 9vw, 6.6rem); font-weight: 400; line-height: .95; letter-spacing: -0.03em; }
.hero h1 em { font-style: italic; font-weight: 300; color: var(--accent); }
.lede { font-size: clamp(1.05rem, 1.6vw, 1.2rem); color: var(--ink-2); max-width: 34ch; margin: 26px 0 30px; }
.hero-links, .contact-links { display: flex; flex-wrap: wrap; gap: 12px; }
.btn {
  display: inline-flex; align-items: center; padding: 11px 20px; border-radius: 999px;
  background: var(--ink); color: var(--bg); text-decoration: none; font-weight: 500; font-size: .95rem;
  border: 1px solid var(--ink); transition: transform .15s, background .15s, color .15s;
}
.btn:hover { transform: translateY(-1px); background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.ghost { background: transparent; color: var(--ink); }
.btn.ghost:hover { color: #fff; }

.ca-figure {
  margin: 0; border: 1px solid var(--line); border-radius: 14px; background: var(--bg-2);
  overflow: hidden; box-shadow: 0 30px 60px -40px rgb(0 0 0 / .35);
}
.cell-io, .ca-figure figcaption { display: flex; gap: 10px; align-items: center; padding: 12px 16px; flex-wrap: wrap; }
.cell-io { border-bottom: 1px solid var(--line); }
.cell-io code { font: inherit; color: var(--ink-2); }
.ca-figure figcaption { border-top: 1px solid var(--line); color: var(--muted); }
.rule {
  font: inherit; color: var(--accent); background: var(--accent-soft); border: 0; border-radius: 4px;
  padding: 1px 6px; cursor: pointer;
}
.rule:hover { background: var(--accent); color: #fff; }
#ca { display: block; width: 100%; aspect-ratio: 1 / 1; cursor: crosshair; image-rendering: pixelated; }

@media (max-width: 860px) {
  .hero { grid-template-columns: 1fr; min-height: 0; padding-top: 40px; }
  #ca { aspect-ratio: 4 / 3; }
}

/* ---------- facts strip ---------- */
.facts { display: grid; grid-template-columns: repeat(4, 1fr); border-top: 1px solid var(--line); }
.facts > div { display: flex; flex-direction: column; gap: 6px; padding: 26px 18px 30px 0; color: var(--ink-2); font-size: .9rem; line-height: 1.35; }
.facts > div + div { padding-left: 18px; border-left: 1px solid var(--line); }
.facts .num { font-family: var(--serif); font-size: 2.1rem; color: var(--ink); line-height: 1; }
@media (max-width: 760px) {
  .facts { grid-template-columns: 1fr 1fr; }
  .facts > div:nth-child(3) { padding-left: 0; border-left: 0; }
  .facts > div:nth-child(n+3) { border-top: 1px solid var(--line); }
}

/* ---------- research ---------- */
.feature {
  padding: clamp(24px, 4vw, 44px); border-radius: 16px; margin-bottom: 28px;
  background:
    radial-gradient(120% 80% at 100% 0%, var(--accent-soft), transparent 60%),
    var(--bg-2);
  border: 1px solid var(--line);
}
.feature h3 { font-size: clamp(1.6rem, 3.4vw, 2.3rem); }
.feature p { max-width: 68ch; color: var(--ink-2); }
.feature .sub { font-family: var(--serif); font-style: italic; font-size: 1.2rem; color: var(--accent-ink); margin: 6px 0 18px; }
.feature-meta, .card-meta { display: flex; flex-wrap: wrap; gap: 6px 18px; color: var(--muted); margin-bottom: 14px; text-transform: uppercase; letter-spacing: .08em; }
.link-arrow { display: inline-flex; gap: 8px; color: var(--accent-ink); font-weight: 500; text-decoration: none; border-bottom: 1px solid currentColor; padding-bottom: 1px; }
.link-arrow::after { content: "→"; transition: transform .2s; }
.link-arrow:hover::after { transform: translateX(4px); }

.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; }
@media (max-width: 760px) { .grid-2 { grid-template-columns: 1fr; } }
.card { padding: 26px; border: 1px solid var(--line); border-radius: 14px; }
.card h3 { margin-bottom: 12px; }
.card p { color: var(--ink-2); }

.minor-head { font-size: 1.15rem; margin: 48px 0 16px; }
.articles { list-style: none; padding: 0; margin: 0 0 10px; }
.articles li { display: grid; grid-template-columns: 64px 1fr; gap: 12px; padding: 14px 0; border-bottom: 1px dashed var(--line); font-family: var(--serif); font-size: 1.08rem; }
.articles .mono { color: var(--muted); padding-top: 4px; }

/* ---------- work timeline ---------- */
.timeline { border-top: 1px solid var(--line); }
.entry { border-bottom: 1px solid var(--line); }
.entry summary {
  display: grid; grid-template-columns: 120px 1fr auto 24px; gap: 16px; align-items: baseline;
  padding: 20px 0; cursor: pointer; list-style: none;
}
.entry summary::-webkit-details-marker { display: none; }
.entry summary::after { content: "+"; font-family: var(--mono); color: var(--accent); text-align: right; transition: transform .2s; }
.entry[open] summary::after { transform: rotate(45deg); }
.entry .when { color: var(--muted); }
.entry .what { font-family: var(--serif); font-size: 1.2rem; }
.entry .org { color: var(--muted); font-size: .9rem; text-align: right; }
.entry summary:hover .what { color: var(--accent-ink); }
.entry .body { padding: 0 40px 24px 136px; color: var(--ink-2); max-width: 900px; }
.entry ul { margin: 0; padding-left: 1.1em; }
.entry h4 { margin: 10px 0 6px; color: var(--accent); font-weight: 500; text-transform: uppercase; letter-spacing: .1em; }
.two-lists { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.award { border-left: 3px solid var(--gold); padding-left: 12px; }
@media (max-width: 760px) {
  .entry summary { grid-template-columns: 1fr 24px; gap: 4px 12px; }
  .entry .when { grid-column: 1; }
  .entry .what { grid-column: 1; }
  .entry .org { grid-column: 1; text-align: left; }
  .entry summary::after { grid-row: 1 / span 3; grid-column: 2; align-self: center; }
  .entry .body { padding: 0 0 22px; }
  .two-lists { grid-template-columns: 1fr; }
}

/* ---------- talks ---------- */
.talks { list-style: none; padding: 0; margin: 0; position: relative; }
.talks::before { content: ""; position: absolute; left: 95px; top: 8px; bottom: 8px; width: 1px; background: var(--line); }
.talks li { display: grid; grid-template-columns: 80px 1fr; gap: 32px; padding: 14px 0; position: relative; }
.talks li::before {
  content: ""; position: absolute; left: 91px; top: 23px; width: 9px; height: 9px; border-radius: 50%;
  background: var(--bg); border: 1px solid var(--muted);
}
.talks li.speaker::before { background: var(--accent); border-color: var(--accent); }
.talks .when { color: var(--muted); padding-top: 5px; text-align: right; }
.talks h3 { font-size: 1.1rem; }
.talks p { color: var(--ink-2); margin: 6px 0 0; font-size: .95rem; }
.tag { display: inline-block; vertical-align: middle; margin-left: 6px; padding: 1px 8px; border-radius: 99px; background: var(--accent-soft); color: var(--accent-ink); font-size: .68rem; text-transform: uppercase; }
@media (max-width: 600px) {
  .talks::before { left: 4px; }
  .talks li { grid-template-columns: 1fr; gap: 2px; padding-left: 26px; }
  .talks li::before { left: 0; top: 20px; }
  .talks .when { text-align: left; }
}

/* ---------- honors ---------- */
.honors { display: grid; grid-template-columns: repeat(3, 1fr); gap: 28px; }
@media (max-width: 900px) { .honors { grid-template-columns: 1fr; } }
.honor-col { padding: 24px; border: 1px solid var(--line); border-radius: 14px; }
.honor-col h3 { font-size: 1.35rem; }
.honor-col .muted { margin: 4px 0 16px; }
.medals, .plain-list { list-style: none; padding: 0; margin: 0; }
.medals li, .plain-list li { display: flex; gap: 12px; align-items: flex-start; padding: 8px 0; border-top: 1px dashed var(--line); font-size: .95rem; }
.plain-list li { display: block; position: relative; padding-left: 22px; }
.plain-list li::before { content: "◆"; color: var(--accent); font-size: .6rem; position: absolute; left: 2px; top: 13px; }
.medal { flex: none; width: 14px; height: 14px; margin-top: 5px; border-radius: 50%; box-shadow: inset 0 0 0 3px rgb(255 255 255 / .25); }
.medal.gold { background: var(--gold); }
.medal.silver { background: var(--silver); }
.medal.bronze { background: var(--bronze); }
.medal.plain { background: var(--muted); }
.medal.captain { background: var(--accent); border-radius: 3px; transform: rotate(45deg) scale(.85); }

/* ---------- volunteering & skills ---------- */
.split { display: grid; grid-template-columns: 1.1fr 1fr; gap: clamp(32px, 6vw, 80px); }
.split .section-head { margin-left: 0; }
@media (max-width: 860px) { .split { grid-template-columns: 1fr; } }
.vol { list-style: none; padding: 0; margin: 0; }
.vol li { padding: 16px 0; border-top: 1px solid var(--line); }
.vol .when { color: var(--accent); }
.vol h3 { font-size: 1.15rem; margin: 4px 0 6px; }
.vol p { color: var(--ink-2); font-size: .95rem; margin: 0; }
.skills { display: grid; grid-template-columns: 110px 1fr; gap: 14px 16px; margin: 0; align-items: center; }
.skills dt { color: var(--muted); text-transform: uppercase; letter-spacing: .08em; }
.skills dd { margin: 0; display: flex; flex-wrap: wrap; gap: 8px; }
.chip { padding: 5px 12px; border: 1px solid var(--line); border-radius: 99px; font-size: .9rem; }
.chip.hot { border-color: var(--accent); color: var(--accent-ink); background: var(--accent-soft); }
.chip small { opacity: .75; }
.langs { list-style: none; padding: 0; margin: 0; }
.langs li { display: grid; grid-template-columns: 80px 1fr 56px; gap: 14px; align-items: center; padding: 8px 0; }
.langs .mono { color: var(--muted); text-align: right; }
.bar { height: 6px; border-radius: 99px; background: var(--line); position: relative; overflow: hidden; }
.bar::after { content: ""; position: absolute; inset: 0; width: calc(var(--v) * 100%); background: var(--ink); border-radius: inherit; }

/* ---------- gallery ---------- */
.gallery { margin: 0; border-radius: 14px; overflow: hidden; border: 1px solid var(--line); }
.gallery img { width: 100%; }
@media (max-width: 600px) {
  .gallery { overflow-x: auto; }
  .gallery img { width: auto; max-width: none; height: 320px; }
}

/* ---------- contact ---------- */
.contact {
  display: grid; grid-template-columns: 240px 1fr; gap: clamp(28px, 5vw, 56px); align-items: center;
  padding-block: clamp(56px, 9vw, 104px); border-top: 1px solid var(--line);
}
.portrait { width: 240px; aspect-ratio: 400 / 438; object-fit: cover; border-radius: 50% 50% 14px 14px; filter: saturate(.9); }
.contact h2 { font-size: clamp(2.2rem, 5vw, 3.6rem); font-weight: 400; margin: 8px 0 12px; }
.contact p { color: var(--ink-2); margin-bottom: 24px; }
@media (max-width: 640px) {
  .contact { grid-template-columns: 1fr; }
  .portrait { width: 180px; }
}

/* ---------- footer ---------- */
.foot {
  display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap;
  max-width: var(--maxw); margin: 0 auto; padding: 28px var(--gutter) 40px;
  border-top: 1px solid var(--line); color: var(--muted);
}

/* ---------- reveal on scroll ---------- */
@media (prefers-reduced-motion: no-preference) {
  .reveal { opacity: 0; transform: translateY(14px); transition: opacity .6s ease, transform .6s ease; }
  .reveal.in { opacity: 1; transform: none; }
}