/* =============================================================
   Ryan Research Group — design system
   "Bold applied-math": warm paper base, ink type, one strong
   signal accent, subtle grid + mono labels, data-viz forward.
   ============================================================= */

:root {
  /* color */
  --paper: #F7F6F1;
  --paper-2: #EFEEE7;
  --ink: #15151A;
  --ink-2: #3C3C45;
  --ink-3: #6B6B76;
  --line: #DEDCD2;
  --accent: #2E5BFF;      /* signal blue */
  --accent-ink: #1F3ECC;
  --hot: #FF5B37;         /* data-viz highlight */
  --green: #12876A;
  --card: #FFFFFF;

  /* type */
  --sans: "Space Grotesk", "Inter", system-ui, sans-serif;
  --body: "Inter", system-ui, -apple-system, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, monospace;

  /* layout */
  --wrap: 1160px;
  --gutter: clamp(20px, 5vw, 64px);
  --radius: 14px;
  --shadow: 0 1px 2px rgba(20,20,26,.05), 0 12px 32px -12px rgba(20,20,26,.14);
  --shadow-lg: 0 2px 4px rgba(20,20,26,.06), 0 30px 60px -20px rgba(20,20,26,.22);
}

/* -------- reset -------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: var(--body);
  color: var(--ink);
  background: var(--paper);
  line-height: 1.6;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: var(--accent-ink); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, h4 { font-family: var(--sans); font-weight: 600; line-height: 1.08; letter-spacing: -0.02em; color: var(--ink); margin: 0 0 .5em; }
h1 { font-size: clamp(2.6rem, 6vw, 4.6rem); }
h2 { font-size: clamp(1.8rem, 3.5vw, 2.7rem); }
h3 { font-size: clamp(1.2rem, 2vw, 1.45rem); }
p { margin: 0 0 1em; }
::selection { background: var(--accent); color: #fff; }

/* -------- helpers -------- */
.wrap { max-width: var(--wrap); margin-inline: auto; padding-inline: var(--gutter); }
.section { padding-block: clamp(64px, 9vw, 120px); }
.eyebrow {
  font-family: var(--mono);
  font-size: .78rem;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--accent-ink);
  margin: 0 0 1rem;
  display: inline-flex;
  align-items: center;
  gap: .55rem;
}
.eyebrow::before { content: ""; width: 26px; height: 2px; background: var(--accent); display: inline-block; }
.lead { font-size: clamp(1.1rem, 1.6vw, 1.3rem); color: var(--ink-2); max-width: 62ch; }
.muted { color: var(--ink-3); }
.mono { font-family: var(--mono); }
.center { text-align: center; }
.grid-bg {
  background-image:
    linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 42px 42px;
  -webkit-mask-image: radial-gradient(ellipse 80% 60% at 50% 40%, #000 40%, transparent 100%);
          mask-image: radial-gradient(ellipse 80% 60% at 50% 40%, #000 40%, transparent 100%);
  opacity: .5;
}

/* -------- buttons -------- */
.btn {
  display: inline-flex; align-items: center; gap: .55rem;
  font-family: var(--sans); font-weight: 600; font-size: .98rem;
  padding: .8rem 1.4rem; border-radius: 100px;
  border: 1.5px solid var(--ink); background: var(--ink); color: #fff;
  cursor: pointer; transition: transform .15s ease, box-shadow .2s ease, background .2s ease;
  text-decoration: none;
}
.btn:hover { transform: translateY(-2px); box-shadow: var(--shadow); text-decoration: none; }
.btn--accent { background: var(--accent); border-color: var(--accent); }
.btn--ghost { background: transparent; color: var(--ink); }
.btn--ghost:hover { background: var(--ink); color: #fff; }
.btn .arw { transition: transform .15s ease; }
.btn:hover .arw { transform: translateX(3px); }

/* -------- top nav -------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  backdrop-filter: saturate(1.4) blur(10px);
  background: rgba(247,246,241,.82);
  border-bottom: 1px solid var(--line);
}
.nav__inner { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding-block: .85rem; }
.brand { display: flex; align-items: center; gap: .65rem; font-family: var(--sans); font-weight: 700; color: var(--ink); letter-spacing: -.02em; }
.brand:hover { text-decoration: none; }
.brand .mark {
  width: 34px; height: 34px; border-radius: 9px; flex: none;
  background: var(--ink); color: #fff; display: grid; place-items: center;
  font-family: var(--mono); font-weight: 700; font-size: .95rem;
}
.brand-mark { width: 40px; height: 40px; flex: none; display: block; }
.brand small { display: block; font-family: var(--mono); font-weight: 400; font-size: .66rem; color: var(--ink-3); letter-spacing: .1em; text-transform: uppercase; }
.nav__links { display: flex; align-items: center; gap: .3rem; }
.nav__links a {
  font-family: var(--sans); font-weight: 500; font-size: .95rem; color: var(--ink-2);
  padding: .5rem .8rem; border-radius: 8px;
}
.nav__links a:hover, .nav__links a[aria-current="page"] { color: var(--ink); background: var(--paper-2); text-decoration: none; }
.nav__cta { margin-left: .4rem; }
.nav__toggle { display: none; background: none; border: 0; cursor: pointer; padding: .4rem; }
.nav__toggle span { display: block; width: 24px; height: 2px; background: var(--ink); margin: 5px 0; transition: .2s; }

/* -------- hero -------- */
.hero { position: relative; overflow: hidden; border-bottom: 1px solid var(--line); }
.hero canvas { position: absolute; inset: 0; width: 100%; height: 100%; z-index: 0; }
.hero__inner { position: relative; z-index: 2; padding-block: clamp(80px, 13vw, 168px); }
.hero__grid { display: grid; grid-template-columns: 1.35fr .95fr; gap: clamp(2rem, 5vw, 4rem); align-items: center; }
.hero h1 { margin-bottom: .35em; }
.hero h1 .grad {
  background: linear-gradient(100deg, var(--accent) 20%, var(--hot) 90%);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero__sub { font-size: clamp(1.1rem, 1.7vw, 1.35rem); color: var(--ink-2); max-width: 46ch; }
.hero__cta { display: flex; flex-wrap: wrap; gap: .8rem; margin-top: 1.8rem; }
.hero__card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow-lg); padding: 1.4rem;
}
.hero__photo { width: 100%; border-radius: 10px; aspect-ratio: 1/1; object-fit: cover; background: var(--paper-2); }
.hero__meta { margin-top: 1rem; font-family: var(--mono); font-size: .8rem; color: var(--ink-3); }
.hero__meta b { color: var(--ink); font-weight: 600; }
.hero__meta div { display: flex; justify-content: space-between; padding: .35rem 0; border-bottom: 1px dashed var(--line); }
.hero__meta div:last-child { border-bottom: 0; }

/* -------- stat strip -------- */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.stat { background: var(--paper); padding: 1.5rem 1.4rem; }
.stat b { font-family: var(--sans); font-size: clamp(1.8rem, 3.5vw, 2.6rem); font-weight: 700; letter-spacing: -.03em; display: block; }
.stat span { font-family: var(--mono); font-size: .74rem; letter-spacing: .06em; text-transform: uppercase; color: var(--ink-3); }
.stat .accent { color: var(--accent); }
.stat .hot { color: var(--hot); }

/* -------- cards / research -------- */
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 1.2rem; }
.cards--2x2 { grid-template-columns: repeat(2, 1fr); }
@media (max-width: 700px) { .cards--2x2 { grid-template-columns: 1fr; } }
.card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 1.6rem; transition: transform .18s ease, box-shadow .22s ease, border-color .2s;
  position: relative; overflow: hidden;
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: #cfcdc2; }
.card__tag { font-family: var(--mono); font-size: .72rem; letter-spacing: .1em; text-transform: uppercase; color: var(--accent-ink); }
.card h3 { margin: .5rem 0 .5rem; }
.card p { color: var(--ink-2); font-size: .97rem; margin-bottom: 0; }
.card__no { position: absolute; top: 1rem; right: 1.2rem; font-family: var(--mono); font-size: .8rem; color: var(--line); font-weight: 700; }
.card--feature { background: var(--ink); color: #fff; }
.card--feature h3, .card--feature .card__tag { color: #fff; }
.card--feature p { color: rgba(255,255,255,.72); }
.card--feature .card__tag { color: #8fa8ff; }

/* -------- split feature (PINN/BINN) -------- */
.split { display: grid; grid-template-columns: 1.1fr .9fr; gap: clamp(2rem,5vw,4rem); align-items: center; }
.panel {
  background: var(--ink); color: #fff; border-radius: var(--radius); padding: clamp(1.6rem, 3vw, 2.6rem);
  position: relative; overflow: hidden;
}
.panel .eyebrow { color: #8fa8ff; }
.panel .eyebrow::before { background: var(--hot); }
.chips { display: flex; flex-wrap: wrap; gap: .5rem; margin-top: 1.2rem; }
.chip { font-family: var(--mono); font-size: .8rem; padding: .35rem .7rem; border: 1px solid rgba(255,255,255,.2); border-radius: 100px; color: rgba(255,255,255,.85); }
.flow { display: flex; align-items: center; gap: .6rem; flex-wrap: wrap; font-family: var(--mono); font-size: .82rem; margin-top: 1.4rem; }
.flow b { background: rgba(255,255,255,.1); border: 1px solid rgba(255,255,255,.18); padding: .5rem .8rem; border-radius: 8px; font-weight: 500; }
.flow .to { color: var(--hot); font-weight: 700; }

/* -------- awards -------- */
.awards { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px,1fr)); gap: 1px; background: var(--line); border-radius: var(--radius); overflow: hidden; border: 1px solid var(--line); }
.award { background: var(--paper); padding: 1.4rem; }
.award .yr { font-family: var(--mono); font-size: .78rem; color: var(--hot); font-weight: 600; }
.award p { margin: .3rem 0 0; font-size: .95rem; font-weight: 500; }

/* -------- publication list -------- */
.pubfilter { display: flex; flex-wrap: wrap; gap: .5rem; margin-bottom: 2rem; }
.pubfilter button {
  font-family: var(--mono); font-size: .82rem; padding: .45rem .9rem; border-radius: 100px;
  border: 1px solid var(--line); background: var(--card); color: var(--ink-2); cursor: pointer; transition: .15s;
}
.pubfilter button:hover { border-color: var(--ink); color: var(--ink); }
.pubfilter button.is-on { background: var(--ink); color: #fff; border-color: var(--ink); }
.publist { list-style: none; margin: 0; padding: 0; }
.pub {
  display: grid; grid-template-columns: auto 1fr; gap: 1.1rem;
  padding: 1.25rem 0; border-bottom: 1px solid var(--line);
}
.pub__no { font-family: var(--mono); color: var(--accent); font-weight: 600; font-size: .95rem; padding-top: .1rem; }
.pub__title { font-weight: 600; color: var(--ink); }
.pub__meta { color: var(--ink-2); font-size: .93rem; }
.pub__venue { font-style: italic; }
.pub__links { margin-top: .35rem; display: flex; flex-wrap: wrap; gap: .5rem; }
.pub__links a { font-family: var(--mono); font-size: .76rem; padding: .2rem .6rem; border: 1px solid var(--line); border-radius: 6px; color: var(--accent-ink); }
.pub__links a:hover { background: var(--accent); color: #fff; border-color: var(--accent); text-decoration: none; }
.pub[hidden] { display: none; }
.pub__badge { font-family: var(--mono); font-size: .68rem; text-transform: uppercase; letter-spacing: .08em; color: var(--hot); border: 1px solid var(--hot); border-radius: 5px; padding: .05rem .4rem; margin-left: .4rem; }

/* -------- section headers -------- */
.sec-head { max-width: 62ch; margin-bottom: 3rem; }
.sec-head--split { display: flex; justify-content: space-between; align-items: flex-end; gap: 2rem; flex-wrap: wrap; max-width: none; }

/* -------- people -------- */
.people { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px,1fr)); gap: 1.2rem; }
.person { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 1.3rem; }
.person .ava { width: 52px; height: 52px; border-radius: 12px; background: var(--paper-2); display: grid; place-items: center; font-family: var(--mono); font-weight: 700; color: var(--accent); margin-bottom: .8rem; }
.person b { display: block; font-family: var(--sans); }
.person span { font-size: .86rem; color: var(--ink-3); }

/* -------- roster (current members) -------- */
.person small { display: block; font-size: .8rem; color: var(--ink-2); margin-top: .3rem; line-height: 1.4; }
.person .role { font-family: var(--mono); font-size: .72rem; letter-spacing: .04em; text-transform: uppercase; color: var(--accent-ink); }
.subhead { font-family: var(--mono); font-size: .78rem; letter-spacing: .14em; text-transform: uppercase; color: var(--ink-3); margin: 2.4rem 0 1rem; display: flex; align-items: center; gap: .8rem; }
.subhead::after { content: ""; flex: 1; height: 1px; background: var(--line); }

/* -------- collaborator cards -------- */
.collab { display: block; text-decoration: none; color: inherit; }
.collab:hover { text-decoration: none; }
.collab h3 { display: flex; align-items: baseline; gap: .35rem; }
.collab h3::after { content: "↗"; font-size: .72em; color: var(--accent); opacity: .35; transition: opacity .15s ease, transform .15s ease; }
.collab:hover h3::after { opacity: 1; transform: translate(1px, -1px); }
.collab-aff { display: block; font-family: var(--mono); font-size: .72rem; letter-spacing: .05em; text-transform: uppercase; color: var(--accent-ink); margin: .15rem 0 .55rem; }

/* -------- notes list (teaching) -------- */
.notes-list { list-style: none; margin: .4rem 0 0; padding: 0; }
.notes-list li { padding: .45rem 0; border-bottom: 1px solid var(--line); }
.notes-list a { font-family: var(--sans); font-weight: 600; }
.notes-list .muted { font-family: var(--body); font-weight: 400; font-size: .9rem; }

/* -------- former members list -------- */
.former { list-style: none; margin: 0; padding: 0; column-gap: 2rem; }
.former li { break-inside: avoid; padding: .55rem 0; border-bottom: 1px solid var(--line); font-size: .95rem; }
.former li b { font-family: var(--sans); font-weight: 600; color: var(--ink); }
.former li .now { color: var(--ink-2); }
.former li .proj { color: var(--ink-3); font-size: .86rem; display: block; margin-top: .1rem; }
.former-cols { columns: 2; column-gap: 2.2rem; }
@media (max-width: 720px) { .former-cols { columns: 1; } }

/* -------- CTA -------- */
.cta { background: var(--ink); color: #fff; border-radius: var(--radius); padding: clamp(2.4rem,5vw,4rem); text-align: center; position: relative; overflow: hidden; }
.cta h2 { color: #fff; }
.cta p { color: rgba(255,255,255,.75); max-width: 54ch; margin-inline: auto; }
.cta .btn--ghost { color: #fff; border-color: rgba(255,255,255,.4); }
.cta .btn--ghost:hover { background: #fff; color: var(--ink); }

/* -------- footer -------- */
.foot { border-top: 1px solid var(--line); padding-block: 3rem 2rem; margin-top: 2rem; position: relative; overflow: hidden; }
.foot .wrap { position: relative; z-index: 1; }
.foot-emblem { position: absolute; right: -34px; bottom: -34px; width: 230px; height: auto; opacity: .05; pointer-events: none; z-index: 0; }
.cta__wordmark { display: block; height: 38px; width: auto; margin: 0 auto 1.2rem; }
.foot__grid { display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 2rem; }
.foot h4 { font-family: var(--mono); font-size: .76rem; text-transform: uppercase; letter-spacing: .1em; color: var(--ink-3); }
.foot a { display: block; color: var(--ink-2); padding: .2rem 0; font-size: .95rem; }
.foot__bottom { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 1rem; margin-top: 2.5rem; padding-top: 1.5rem; border-top: 1px solid var(--line); font-size: .85rem; color: var(--ink-3); }

/* -------- reveal animation -------- */
.reveal { opacity: 0; transform: translateY(22px); transition: opacity .6s ease, transform .6s ease; }
.reveal.in { opacity: 1; transform: none; }

/* -------- page header (interior) -------- */
.phead { border-bottom: 1px solid var(--line); position: relative; overflow: hidden; }
.phead__inner { padding-block: clamp(60px, 8vw, 96px); position: relative; z-index: 2; }
.phead .abs-grid { position: absolute; inset: 0; z-index: 0; }
.phead-emblem { position: absolute; right: -28px; top: 50%; transform: translateY(-50%); width: min(300px, 32vw); opacity: .5; z-index: 1; pointer-events: none; }
@media (max-width: 820px) { .phead-emblem { display: none; } }

/* -------- prose (research detail) -------- */
.prose { max-width: 70ch; }
.prose h3 { margin-top: 2.4rem; }
.prose p { color: var(--ink-2); }
.topic { border-left: 3px solid var(--accent); padding-left: 1.4rem; margin: 2.6rem 0; }
.topic:nth-child(even) { border-color: var(--hot); }

/* -------- figures -------- */
.figs { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: 1rem; margin: 1.6rem 0 .4rem; }
.fig {
  background: var(--card); border: 1px solid var(--line); border-radius: 12px;
  overflow: hidden; margin: 0;
}
.fig img { width: 100%; height: 190px; object-fit: contain; background: #fff; padding: .6rem; display: block; }
.fig figcaption { font-family: var(--mono); font-size: .74rem; color: var(--ink-3); padding: .6rem .8rem .8rem; border-top: 1px solid var(--line); line-height: 1.4; }
.fig figcaption b { color: var(--ink); font-weight: 600; }
.fig--wide { grid-column: 1 / -1; }
.fig--wide img { height: auto; max-height: 340px; }

/* -------- demo widget -------- */
.demo { display: grid; grid-template-columns: 1.1fr .9fr; gap: 1.5rem; align-items: stretch; }
.demo__stage { background: var(--ink); border-radius: var(--radius); padding: 1.2rem; position: relative; overflow: hidden; }
.demo__stage canvas { width: 100%; height: auto; display: block; border-radius: 8px; background: #0e0e12; }
.demo__panel { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 1.4rem; }
.demo__row { margin: 1.1rem 0; }
.demo__row label { display: flex; justify-content: space-between; font-family: var(--mono); font-size: .8rem; color: var(--ink-2); margin-bottom: .4rem; }
.demo__row label b { color: var(--accent-ink); }
.demo input[type=range] { width: 100%; accent-color: var(--accent); }
.demo__eq { background: var(--paper-2); border: 1px solid var(--line); border-radius: 10px; padding: 1rem; font-family: var(--mono); font-size: .92rem; margin-top: 1rem; line-height: 1.7; }
.demo__eq .rec { color: var(--hot); font-weight: 600; }
.demo__eq small { color: var(--ink-3); font-size: .74rem; }
.demo__stat { display: flex; gap: 1.2rem; margin-top: 1rem; font-family: var(--mono); font-size: .78rem; color: rgba(255,255,255,.7); }
.demo__stat b { color: #fff; display: block; font-size: 1.15rem; }
.legend { display: flex; gap: 1.2rem; font-family: var(--mono); font-size: .74rem; color: rgba(255,255,255,.7); margin-top: .8rem; }
.legend i { display: inline-block; width: 22px; height: 3px; border-radius: 2px; vertical-align: middle; margin-right: .35rem; }
@media (max-width: 820px) { .demo { grid-template-columns: 1fr; } }

/* -------- responsive -------- */
@media (max-width: 900px) {
  .hero__grid { grid-template-columns: 1fr; }
  .hero__card { max-width: 360px; }
  .split { grid-template-columns: 1fr; }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .foot__grid { grid-template-columns: 1fr 1fr; }
  .nav__links { position: fixed; inset: 61px 0 auto 0; flex-direction: column; align-items: stretch; background: var(--paper); border-bottom: 1px solid var(--line); padding: 1rem var(--gutter); gap: .2rem; transform: translateY(-120%); transition: transform .25s ease; }
  .nav__links.open { transform: none; }
  .nav__links a { padding: .8rem; }
  .nav__toggle { display: block; }
}
@media (max-width: 560px) {
  .stats { grid-template-columns: 1fr 1fr; }
  .foot__grid { grid-template-columns: 1fr; }
  .pub { grid-template-columns: 1fr; gap: .3rem; }
  .hero__cta .btn, .hero__cta { width: 100%; }
  .hero__cta .btn { justify-content: center; }
}
/* long-token safety so nothing clips on narrow screens */
.former li, .pub__meta, .pub__title, .person small, .card p, .hero__meta b { overflow-wrap: anywhere; }
@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; }
}