/* ==========================================================================
   Inference Lab — Sungkyunkwan University
   Single stylesheet. No external fonts, no CDN, no build step.
   Light palette on bare :root; dark redefined under prefers-color-scheme.
   ========================================================================== */

:root {
  --bg:        #fbfbfa;
  --bg-raised: #ffffff;
  --bg-sunken: #f2f2f0;
  --text:      #1a1a1c;
  --text-mute: #5c5c66;
  --text-faint:#84848f;
  --rule:      #e2e2df;
  --accent:    #2d4a7c;
  --accent-lo: #eaeff7;
  --accent-hi: #1c3057;

  --measure: 34rem;
  --wide: 60rem;

  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, "Times New Roman", serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg:        #131316;
    --bg-raised: #1b1b20;
    --bg-sunken: #0e0e11;
    --text:      #ececf0;
    --text-mute: #a6a6b2;
    --text-faint:#7b7b88;
    --rule:      #2c2c34;
    --accent:    #93b2e6;
    --accent-lo: #1c2436;
    --accent-hi: #b9cdf2;
  }
}

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

/* ---------- layout ---------- */

.wrap {
  max-width: var(--wide);
  margin: 0 auto;
  padding: 0 1.5rem;
}

main { padding-bottom: 5rem; }

section { margin-top: 3.5rem; }

/* ---------- masthead ---------- */

.masthead {
  border-bottom: 1px solid var(--rule);
  background: var(--bg-raised);
}

.masthead-inner {
  max-width: var(--wide);
  margin: 0 auto;
  padding: 1.4rem 1.5rem 0;
}

.brand {
  display: flex;
  align-items: baseline;
  gap: 0.75rem;
  flex-wrap: wrap;
  text-decoration: none;
  color: inherit;
}

.brand-name {
  font-family: var(--serif);
  font-size: 1.5rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--text);
}

.brand-affil {
  font-size: 0.85rem;
  color: var(--text-faint);
}

nav.site {
  display: flex;
  gap: 1.6rem;
  flex-wrap: wrap;
  margin-top: 1rem;
}

nav.site a {
  display: inline-block;
  padding-bottom: 0.7rem;
  font-size: 0.94rem;
  color: var(--text-mute);
  text-decoration: none;
  border-bottom: 2px solid transparent;
}

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

nav.site a[aria-current="page"] {
  color: var(--accent);
  border-bottom-color: var(--accent);
  font-weight: 600;
}

/* ---------- hero ---------- */

.hero {
  padding: 3.5rem 0 0.5rem;
}

.claim {
  font-family: var(--serif);
  font-size: clamp(1.4rem, 3.4vw, 2.05rem);
  line-height: 1.4;
  font-weight: 500;
  letter-spacing: -0.015em;
  margin: 0;
  max-width: 40rem;
}

.claim em {
  font-style: normal;
  color: var(--accent);
}

.hero-sub {
  margin-top: 1.4rem;
  max-width: var(--measure);
  color: var(--text-mute);
}

/* ---------- typography ---------- */

h1, h2, h3 { letter-spacing: -0.012em; }

h1 {
  font-family: var(--serif);
  font-size: 2.1rem;
  font-weight: 600;
  margin: 3rem 0 0.5rem;
}

h2 {
  font-size: 1.32rem;
  font-weight: 650;
  margin: 0 0 1.1rem;
  padding-bottom: 0.45rem;
  border-bottom: 1px solid var(--rule);
}

h3 {
  font-size: 1.03rem;
  font-weight: 650;
  margin: 1.8rem 0 0.4rem;
}

p { max-width: var(--measure); }
.wide p, p.wide { max-width: 46rem; }

a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { color: var(--accent-hi); }

.lede { font-size: 1.06rem; color: var(--text-mute); }

.eyebrow {
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin: 0 0 0.35rem;
}

strong { font-weight: 650; }

/* ---------- layer cards ---------- */

.layers {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  gap: 1.1rem;
  margin-top: 1.5rem;
}

.layer {
  background: var(--bg-raised);
  border: 1px solid var(--rule);
  border-radius: 10px;
  padding: 1.3rem 1.35rem 1.45rem;
}

.layer .num {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--accent);
  letter-spacing: 0.04em;
}

.layer h3 { margin: 0.35rem 0 0.5rem; font-size: 1.08rem; }
.layer p { margin: 0; font-size: 0.94rem; color: var(--text-mute); max-width: none; }
.layer .years {
  display: block;
  margin-top: 0.9rem;
  font-size: 0.78rem;
  color: var(--text-faint);
  font-family: var(--mono);
}

/* ---------- pull quote / highlight ---------- */

.pull {
  margin: 2.5rem 0 0;
  padding: 1.4rem 1.6rem;
  background: var(--accent-lo);
  border-left: 3px solid var(--accent);
  border-radius: 0 8px 8px 0;
}

.pull p { margin: 0; max-width: 44rem; }

/* ---------- callout ---------- */

.callout {
  margin-top: 3rem;
  padding: 1.5rem 1.6rem;
  background: var(--bg-raised);
  border: 1px solid var(--rule);
  border-radius: 10px;
}

.callout h2 { border: 0; margin-bottom: 0.5rem; padding: 0; }
.callout p { margin: 0 0 1rem; }

.btn {
  display: inline-block;
  padding: 0.55rem 1.1rem;
  background: var(--accent);
  color: var(--bg-raised);
  border-radius: 7px;
  font-size: 0.92rem;
  font-weight: 600;
  text-decoration: none;
}

.btn:hover { background: var(--accent-hi); color: var(--bg-raised); }

@media (prefers-color-scheme: dark) {
  .btn { color: #0e0e11; }
  .btn:hover { color: #0e0e11; }
}

/* ---------- news ---------- */

.news { list-style: none; padding: 0; margin: 1.2rem 0 0; max-width: 46rem; }

.news li {
  display: grid;
  grid-template-columns: 6.5rem 1fr;
  gap: 0.9rem;
  padding: 0.7rem 0;
  border-bottom: 1px solid var(--rule);
  font-size: 0.95rem;
}

.news .when {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--text-faint);
  padding-top: 0.15rem;
}

/* ---------- publications ---------- */

.pubyear {
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--text-faint);
  margin: 2.4rem 0 0.6rem;
  letter-spacing: 0.05em;
}

.pub {
  padding: 0.85rem 0;
  border-bottom: 1px solid var(--rule);
  max-width: 46rem;
}

.pub-title { display: block; font-weight: 600; margin-bottom: 0.15rem; }
.pub-authors { display: block; font-size: 0.9rem; color: var(--text-mute); }
.pub-venue { display: block; font-size: 0.9rem; color: var(--text-faint); font-style: italic; }

.tag {
  display: inline-block;
  margin-top: 0.4rem;
  padding: 0.1rem 0.5rem;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  border-radius: 4px;
  background: var(--accent-lo);
  color: var(--accent);
}

.me { border-bottom: 2px solid var(--accent); }

/* ---------- project blocks ---------- */

.project {
  margin-top: 1.6rem;
  padding: 1.3rem 1.4rem;
  background: var(--bg-raised);
  border: 1px solid var(--rule);
  border-radius: 10px;
}

.project h3 { margin-top: 0; }
.project p { max-width: 44rem; }
.project p:last-child { margin-bottom: 0; }

/* ---------- courses ---------- */

.course {
  margin-top: 1.5rem;
  padding: 1.3rem 1.4rem;
  background: var(--bg-raised);
  border: 1px solid var(--rule);
  border-radius: 10px;
}

.course h3 { margin-top: 0; margin-bottom: 0.15rem; }
.course .code {
  font-family: var(--mono);
  font-size: 0.76rem;
  color: var(--text-faint);
  letter-spacing: 0.04em;
}
.course p { max-width: 44rem; }
.course p:last-child { margin-bottom: 0; }

.demos {
  list-style: none;
  padding: 0;
  margin: 1rem 0 0;
  border-top: 1px solid var(--rule);
  padding-top: 0.9rem;
}

.demos-label {
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin: 1rem 0 0;
}

.demos li { margin: 0.4rem 0; font-size: 0.94rem; }
.demos li::before { content: "▸"; color: var(--accent); margin-right: 0.5rem; }

.demos-empty {
  font-size: 0.9rem;
  color: var(--text-faint);
  font-style: italic;
  margin: 0.5rem 0 0;
}

/* ---------- lists ---------- */

ul.plain { max-width: var(--measure); padding-left: 1.15rem; }
ul.plain li { margin-bottom: 0.45rem; }

dl.facts { max-width: 46rem; margin: 1.2rem 0 0; }
dl.facts dt {
  font-weight: 650;
  font-size: 0.94rem;
  margin-top: 1.1rem;
}
dl.facts dd { margin: 0.2rem 0 0; color: var(--text-mute); }

/* ---------- tables that must not break the page ---------- */

.scroller { overflow-x: auto; }

/* ---------- footer ---------- */

footer.site {
  border-top: 1px solid var(--rule);
  background: var(--bg-sunken);
  padding: 2rem 0;
  margin-top: 4rem;
}

footer.site .wrap { display: flex; justify-content: space-between; gap: 1rem; flex-wrap: wrap; }
footer.site p { margin: 0; font-size: 0.85rem; color: var(--text-faint); max-width: none; }

/* ---------- small screens ---------- */

@media (max-width: 34rem) {
  body { font-size: 16px; }
  .hero { padding-top: 2.5rem; }
  .news li { grid-template-columns: 1fr; gap: 0.15rem; }
  nav.site { gap: 1.1rem; }
}