/* Quantum Gravity & Holography — Sogang University
   Palette: cool ink, Sogang crimson, slate neutrals
   Type: Spectral (display) / IBM Plex Sans (body) / IBM Plex Mono (data) */

:root {
  --ground:      #f4f6f8;
  --surface:     #ffffff;
  --surface-alt: #eceff3;
  --ink:         #151a22;
  --ink-soft:    #3d4654;
  --muted:       #6b7686;
  --line:        #dde2e9;
  --line-strong: #c3cbd6;
  --accent:      #8f1a26;
  --accent-ink:  #ffffff;
  --accent-wash: #f6e9ea;

  --font-display: "Spectral", Georgia, "Times New Roman", serif;
  --font-body: "IBM Plex Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  --shell: 1080px;
  --prose: 68ch;
  --radius: 3px;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --ground:      #0f131a;
    --surface:     #161b24;
    --surface-alt: #1c222d;
    --ink:         #e7eaef;
    --ink-soft:    #bcc4d0;
    --muted:       #8d97a6;
    --line:        #262d39;
    --line-strong: #38414f;
    --accent:      #e0737d;
    --accent-ink:  #1a0d0f;
    --accent-wash: #241419;
  }
}

:root[data-theme="dark"] {
  --ground:      #0f131a;
  --surface:     #161b24;
  --surface-alt: #1c222d;
  --ink:         #e7eaef;
  --ink-soft:    #bcc4d0;
  --muted:       #8d97a6;
  --line:        #262d39;
  --line-strong: #38414f;
  --accent:      #e0737d;
  --accent-ink:  #1a0d0f;
  --accent-wash: #241419;
}

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

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

body {
  margin: 0;
  background: var(--ground);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.65;
  font-feature-settings: "kern" 1;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; height: auto; display: block; }

a { color: var(--ink); text-decoration-color: var(--line-strong); text-underline-offset: 3px; }
a:hover { text-decoration-color: var(--accent); color: var(--accent); }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.2;
  text-wrap: balance;
  margin: 0;
  letter-spacing: -0.01em;
}

p { margin: 0; }

.wrap {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: 24px;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}

/* ---------- header ---------- */

.site-head {
  border-bottom: 1px solid var(--line);
  background: var(--surface);
  position: sticky;
  top: 0;
  z-index: 20;
}

.site-head .wrap {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 28px;
  padding-block: 16px;
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 1px;
  text-decoration: none;
  margin-right: auto;
}
.brand:hover { color: inherit; }
.brand b {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 600;
  letter-spacing: -0.015em;
  line-height: 1.15;
}
.brand span {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
}

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 20px;
  align-items: baseline;
}
.nav a {
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
  color: var(--ink-soft);
  padding-bottom: 3px;
  border-bottom: 2px solid transparent;
  white-space: nowrap;
}
.nav a:hover { color: var(--accent); }
.nav a[aria-current="page"] {
  color: var(--ink);
  border-bottom-color: var(--accent);
}

/* ---------- page heading ---------- */

.page-head {
  border-bottom: 1px solid var(--line);
  background: var(--surface);
}
.page-head .wrap {
  padding-block: 44px 36px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.page-head h1 { font-size: clamp(30px, 5vw, 42px); }
.page-head .lede {
  max-width: min(96ch, 100%);
  color: var(--ink-soft);
  font-size: 17px;
}

main { display: block; }

.section {
  padding-block: 52px;
  border-bottom: 1px solid var(--line);
}
.section:last-of-type { border-bottom: none; }
.section > .wrap { display: flex; flex-direction: column; gap: 26px; }

.section-title { font-size: 25px; }

.prose { max-width: var(--prose); display: flex; flex-direction: column; gap: 16px; }
.prose p { color: var(--ink-soft); }
.prose strong { color: var(--ink); font-weight: 600; }

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

.hero {
  background: var(--surface);
  border-bottom: 1px solid var(--line);
  overflow: hidden;
}
.hero .wrap {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
  gap: 48px;
  align-items: center;
  padding-block: 64px 60px;
}
.hero-copy { display: flex; flex-direction: column; gap: 20px; }
.hero h1 {
  font-size: clamp(32px, 5.4vw, 50px);
  letter-spacing: -0.02em;
}
.hero h1 em {
  font-style: italic;
  color: var(--accent);
}
.hero .lede {
  font-size: 18px;
  color: var(--ink-soft);
  max-width: 54ch;
}

.hero-figure { display: flex; flex-direction: column; gap: 10px; align-items: center; }
.hero-figure canvas {
  width: 100%;
  max-width: 320px;
  aspect-ratio: 1;
  display: block;
}
.hero-figure figcaption {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  text-align: center;
}

.actions { display: flex; flex-wrap: wrap; gap: 10px; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
  padding: 9px 16px;
  border-radius: var(--radius);
  border: 1px solid var(--line-strong);
  color: var(--ink);
  background: var(--surface);
}
.btn:hover { border-color: var(--accent); color: var(--accent); }
.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-ink);
}
.btn-primary:hover { background: var(--accent); color: var(--accent-ink); opacity: 0.88; }

/* ---------- topic list (home + research) ---------- */

.topics {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}
.topic {
  background: var(--surface);
  padding: 24px 26px 26px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.topic h3 { font-size: 18.5px; }
.topic p { color: var(--ink-soft); font-size: 15px; }

@media (min-width: 760px) {
  .topics { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

/* ---------- people ---------- */

.roster { display: flex; flex-direction: column; gap: 0; }

.role-group {
  border-top: 1px solid var(--line);
  padding-block: 24px;
  display: grid;
  grid-template-columns: 200px minmax(0, 1fr);
  gap: 12px 32px;
  align-items: start;
}
.role-group:first-child { border-top: none; padding-top: 4px; }

.role-label {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  padding-top: 4px;
}

.role-people { display: flex; flex-direction: column; gap: 22px; }

.person { display: flex; flex-direction: column; gap: 5px; }
.person .name {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 600;
  letter-spacing: -0.01em;
}
.person .name .ko { color: var(--muted); font-weight: 500; font-size: 16px; }
.person .term {
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}
.person .term span { display: block; }

.person-links { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 4px; }

.chip {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.04em;
  text-decoration: none;
  padding: 3px 9px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  color: var(--ink-soft);
  background: var(--surface);
  white-space: nowrap;
}
.chip:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-wash); }

.cv-block { display: flex; flex-direction: column; gap: 4px; margin-top: 8px; }
.cv-block dl {
  margin: 0;
  display: grid;
  grid-template-columns: max-content minmax(0, 1fr);
  gap: 2px 16px;
  font-size: 14.5px;
}
.cv-block dt {
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
  padding-top: 2px;
}
.cv-block dd { margin: 0; color: var(--ink-soft); }
.cv-block h4 {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 500;
  margin-top: 10px;
}

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

.year-block {
  display: grid;
  grid-template-columns: 200px minmax(0, 1fr);
  gap: 14px 32px;
  align-items: start;
  border-top: 1px solid var(--line);
  padding-block: 26px;
}
.year-block:first-child { border-top: none; padding-top: 4px; }

.year-num {
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 500;
  font-variant-numeric: tabular-nums;
  color: var(--accent);
  letter-spacing: 0.02em;
  position: sticky;
  top: 84px;
}
.year-num small {
  display: block;
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  margin-top: 2px;
}

.pub-list { display: flex; flex-direction: column; gap: 24px; }

.pub { display: flex; flex-direction: column; gap: 5px; }
.pub .title {
  font-family: var(--font-display);
  font-size: 17.5px;
  font-weight: 600;
  line-height: 1.35;
  color: var(--ink);
  max-width: 62ch;
}
.pub .authors { font-size: 14.5px; color: var(--muted); max-width: 68ch; }
.pub .authors b { color: var(--ink-soft); font-weight: 600; }
.pub .ref {
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--ink-soft);
  font-variant-numeric: tabular-nums;
}
.pub .ref .preprint { color: var(--accent); }
.pub-links { display: flex; flex-wrap: wrap; gap: 7px; margin-top: 3px; }

/* ---------- teaching ---------- */

.course-list { display: flex; flex-direction: column; }
.course {
  display: grid;
  grid-template-columns: 200px minmax(0, 1fr);
  gap: 8px 32px;
  align-items: start;
  border-top: 1px solid var(--line);
  padding-block: 22px;
}
.course:first-child { border-top: none; padding-top: 4px; }
.course .term-label {
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.06em;
  color: var(--accent);
  font-variant-numeric: tabular-nums;
  padding-top: 3px;
}
.course h3 { font-size: 18px; }
.course p { color: var(--ink-soft); font-size: 15px; max-width: 62ch; margin-top: 5px; }

.note {
  border-left: 3px solid var(--accent);
  background: var(--accent-wash);
  padding: 14px 18px;
  font-size: 14.5px;
  color: var(--ink-soft);
  max-width: var(--prose);
}

/* ---------- join / contact ---------- */

.contact-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 26px 28px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-width: var(--prose);
}
.contact-card h3 { font-size: 20px; }
.contact-card p { color: var(--ink-soft); font-size: 15px; }
.contact-card a.mail {
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--accent);
  text-decoration-color: var(--accent);
  word-break: break-all;
}

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

.site-foot {
  border-top: 1px solid var(--line);
  background: var(--surface-alt);
  margin-top: 0;
}
.site-foot .wrap {
  padding-block: 30px 36px;
  display: flex;
  flex-wrap: wrap;
  gap: 18px 48px;
  justify-content: space-between;
  align-items: flex-start;
}
.site-foot .addr {
  font-size: 13.5px;
  color: var(--muted);
  line-height: 1.7;
  font-style: normal;
}
.site-foot .addr b { display: block; color: var(--ink-soft); font-weight: 600; font-size: 14px; }
.site-foot .foot-links { display: flex; flex-direction: column; gap: 4px; font-size: 13.5px; }
.site-foot .foot-links a { color: var(--muted); text-decoration: none; }
.site-foot .foot-links a:hover { color: var(--accent); }
.site-foot .copy {
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.06em;
  color: var(--muted);
  width: 100%;
  padding-top: 14px;
  border-top: 1px solid var(--line);
}

/* ---------- responsive ---------- */

@media (max-width: 860px) {
  .hero .wrap { grid-template-columns: minmax(0, 1fr); gap: 36px; padding-block: 44px; }
  .hero-figure { order: -1; align-items: flex-start; }
  .hero-figure figcaption { text-align: left; }
  .year-block, .role-group, .course {
    grid-template-columns: minmax(0, 1fr);
    gap: 10px;
  }
  .year-num { position: static; }
  .cv-block dl { grid-template-columns: minmax(0, 1fr); gap: 0 0; }
  .cv-block dt { padding-top: 8px; }
}

@media (max-width: 560px) {
  .wrap { padding-inline: 18px; }
  .site-head .wrap { padding-block: 12px; }
  .nav { gap: 4px 14px; }
  .section { padding-block: 38px; }
}

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

/* ---------- teaching (institution groups) ---------- */

.inst-group {
  display: grid;
  grid-template-columns: 200px minmax(0, 1fr);
  gap: 14px 32px;
  align-items: start;
  border-top: 1px solid var(--line);
  padding-block: 26px;
}
.inst-group:first-child { border-top: none; padding-top: 4px; }

.inst-label {
  position: sticky;
  top: 84px;
}
.inst-label b {
  display: block;
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 600;
  letter-spacing: -0.01em;
}
.inst-label span {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  margin-top: 3px;
}

.course-rows {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 150px max-content;
  column-gap: 0;
  align-items: start;
  max-width: 880px;
}
.course-rows.lectures { grid-template-columns: minmax(0, 1fr) minmax(0, 1.3fr) max-content; }
.course-rows.lectures .who { white-space: normal; }
.course-row { display: contents; }
.course-row > div {
  border-top: 1px solid var(--line);
  padding-block: 12px;
  line-height: 24px;
}
.course-row > .what,
.course-row > .who { padding-right: 28px; }
.course-row:first-child > div { border-top: none; padding-top: 0; }
.course-row .what { font-size: 16px; color: var(--ink); }
.course-row .who {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}
.course-row .when {
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--accent);
  font-variant-numeric: tabular-nums;
  text-align: right;
  white-space: nowrap;
}

.sup-cat { display: flex; flex-direction: column; gap: 4px; }
.sup-cat h4 {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
}
.sup-cat ul { margin: 0; padding: 0; list-style: none; display: flex; flex-direction: column; gap: 3px; }
.sup-cat li { font-size: 15px; color: var(--ink-soft); }
.sup-cat li b { color: var(--ink); font-weight: 600; }
.sup-cat li span {
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}
.sup-groups { display: flex; flex-direction: column; gap: 18px; }

.award-note {
  display: flex;
  gap: 12px;
  align-items: baseline;
  border-left: 3px solid var(--accent);
  padding: 12px 0 12px 16px;
  max-width: var(--prose);
}
.award-note .medal {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  white-space: nowrap;
}
.award-note p { font-size: 15px; color: var(--ink-soft); }

@media (max-width: 860px) {
  .inst-group { grid-template-columns: minmax(0, 1fr); }
  .inst-label { position: static; }
  .course-rows, .course-rows.lectures { grid-template-columns: minmax(0, 1fr); }
  .course-row > .what, .course-row > .who { padding-right: 0; }
  .course-row > div { border-top: none; padding-block: 2px; }
  .course-row > .what { border-top: 1px solid var(--line); padding-top: 14px; }
  .course-row:first-child > .what { border-top: none; padding-top: 0; }
  .course-row > .when {
    text-align: left;
    white-space: normal;
    padding-bottom: 14px;
  }
  .award-note { flex-direction: column; gap: 6px; }
}

/* ---------- portraits ---------- */

.person {
  display: flex;
  flex-direction: row;
  align-items: flex-start;
  gap: 20px;
}
.person-body { display: flex; flex-direction: column; gap: 5px; min-width: 0; }

.portrait {
  flex: none;
  width: 92px;
  aspect-ratio: 4 / 5;
  object-fit: cover;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface-alt);
  height: auto;
}
.person.is-pi .portrait { width: 132px; }

@media (max-width: 560px) {
  .person { gap: 14px; }
  .portrait { width: 76px; }
  .person.is-pi .portrait { width: 96px; }
}