:root {
  --bg: #ffffff;
  --surface: #f6f7f8;
  --text: #15171a;
  --muted: #60666e;
  --line: #e2e5e9;
  --accent: #155eef;
  --accent-soft: #eaf1ff;
  --max: 1120px;
  --radius: 18px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 96px; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans KR", "Malgun Gothic", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
a:hover { color: var(--accent); }
img { max-width: 100%; }
button { font: inherit; }

[data-lang="ko"] { display: none; }
html[data-language="ko"] [data-lang="en"] { display: none !important; }
html[data-language="ko"] [data-lang="ko"] { display: inline; }
html[data-language="ko"] p[data-lang="ko"],
html[data-language="ko"] div[data-lang="ko"] { display: block; }

.skip-link {
  position: fixed;
  left: 16px;
  top: -60px;
  z-index: 1000;
  background: var(--text);
  color: white;
  padding: 8px 12px;
  border-radius: 8px;
}
.skip-link:focus { top: 16px; }

.shell { width: min(calc(100% - 48px), var(--max)); margin: 0 auto; }
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,.92);
  border-bottom: 1px solid rgba(226,229,233,.85);
  backdrop-filter: blur(14px);
}
.nav-shell {
  min-height: 72px;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 28px;
}
.brand { font-weight: 700; letter-spacing: -.025em; font-size: 18px; }
.site-nav { display: flex; justify-content: flex-end; gap: 24px; font-size: 14px; font-weight: 500; color: #3f444b; }
.site-nav a { white-space: nowrap; }
.language-switch {
  display: flex;
  align-items: center;
  gap: 6px;
  padding-left: 20px;
  border-left: 1px solid var(--line);
  color: #858b93;
  font-size: 13px;
}
.language-switch button {
  padding: 4px 2px;
  border: 0;
  background: transparent;
  color: #858b93;
  cursor: pointer;
}
.language-switch button.active { color: var(--text); font-weight: 700; }

.hero { padding: 116px 0 104px; }
.eyebrow, .section-label {
  color: var(--accent);
  font-weight: 700;
  font-size: 12px;
  letter-spacing: .11em;
  text-transform: uppercase;
}
.hero h1 {
  margin: 17px 0 14px;
  font-size: clamp(52px, 8vw, 92px);
  line-height: .98;
  letter-spacing: -.065em;
  max-width: 950px;
}
.name-ko {
  font-family: "Segoe UI", "Noto Sans KR", "Malgun Gothic", Arial, sans-serif;
  font-size: .34em;
  font-weight: 500;
  letter-spacing: -.05em;
  vertical-align: .34em;
  color: #8b9199;
  margin-left: 10px;
}
.hero-role { margin: 24px 0 0; font-size: 18px; line-height: 1.55; font-weight: 600; color: #30353b; }
.hero-statement {
  max-width: 820px;
  margin: 32px 0 0;
  font-size: clamp(21px, 3vw, 30px);
  line-height: 1.48;
  letter-spacing: -.025em;
  color: #3e444b;
}
.hero-links { margin-top: 40px; display: flex; align-items: center; flex-wrap: wrap; gap: 12px; }
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 18px;
  border-radius: 999px;
  border: 1px solid var(--line);
  font-size: 14px;
  font-weight: 600;
  background: white;
}
.button.primary { background: var(--text); color: white; border-color: var(--text); }
.button.primary:hover { background: var(--accent); border-color: var(--accent); color: white; }
.text-link { margin-left: 8px; font-size: 14px; font-weight: 600; color: #4e545c; }

.section { padding: 104px 0; border-top: 1px solid var(--line); }
.section-tint { background: var(--surface); border-top: 0; }
.intro { display: grid; grid-template-columns: 180px minmax(0, 1fr); gap: 48px; }
.section-content { min-width: 0; }
.large-prose { max-width: 830px; }
.large-prose > p { font-size: 21px; letter-spacing: -.015em; color: #33383e; margin: 0 0 24px; }
.large-prose > p:last-of-type { margin-bottom: 42px; }
.facts { border-top: 1px solid var(--line); }
.facts > div { display: grid; grid-template-columns: 130px 1fr; gap: 18px; padding: 16px 0; border-bottom: 1px solid var(--line); font-size: 14px; }
.fact-label { color: var(--muted); font-weight: 600; }

.section-heading-row {
  display: grid;
  grid-template-columns: minmax(300px, .9fr) minmax(300px, 1.1fr);
  gap: 80px;
  align-items: end;
  margin-bottom: 50px;
}
.section-heading-row h2, .contact h2 { margin: 12px 0 0; font-size: clamp(34px, 5vw, 52px); line-height: 1.08; letter-spacing: -.045em; }
.section-deck { margin: 0; color: var(--muted); font-size: 17px; max-width: 620px; }

.research-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); border-top: 1px solid #d7dbe0; border-left: 1px solid #d7dbe0; }
.research-card { min-height: 340px; padding: 34px; border-right: 1px solid #d7dbe0; border-bottom: 1px solid #d7dbe0; background: rgba(255,255,255,.45); }
.card-index { display: block; font-size: 12px; color: #8c929a; margin-bottom: 64px; font-variant-numeric: tabular-nums; }
.research-card h3 { margin: 0 0 18px; font-size: 24px; line-height: 1.3; letter-spacing: -.025em; }
.research-card p { color: #5b6168; margin: 0; }
.tags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 28px; }
.tags span { background: white; border: 1px solid #dfe3e7; border-radius: 999px; padding: 5px 10px; color: #646b73; font-size: 11px; font-weight: 600; }

.publications-heading { margin-bottom: 30px; }
.publication-list { border-top: 1px solid var(--text); }
.publication { display: grid; grid-template-columns: 74px 1fr 110px; gap: 30px; padding: 25px 0 27px; border-bottom: 1px solid var(--line); align-items: start; }
.pub-year { font-size: 14px; font-weight: 700; font-variant-numeric: tabular-nums; }
.pub-main h3 { margin: 0 0 7px; font-size: 17px; line-height: 1.5; letter-spacing: -.012em; font-weight: 600; }
.pub-main p { margin: 0; color: var(--muted); font-size: 13px; }
.pub-venue { text-align: right; color: var(--accent); font-size: 12px; font-weight: 700; }

.teaching-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.teaching-grid article { background: white; border: 1px solid #dde1e5; border-radius: var(--radius); padding: 30px; min-height: 260px; }
.course-code { display: inline-block; padding: 4px 8px; border-radius: 6px; background: var(--accent-soft); color: var(--accent); font-size: 11px; font-weight: 700; }
.teaching-grid h3 { margin: 50px 0 12px; font-size: 21px; line-height: 1.3; letter-spacing: -.025em; }
.teaching-grid p { margin: 0; color: var(--muted); font-size: 14px; }

.contact { padding-bottom: 120px; }
.contact-grid { display: grid; grid-template-columns: 1.25fr .75fr; gap: 80px; margin-top: 12px; align-items: end; }
.contact-grid > div:first-child p { max-width: 620px; color: var(--muted); font-size: 17px; }
.contact-details { display: flex; flex-direction: column; gap: 20px; font-size: 14px; color: #4e545c; }
.contact-details > a { font-size: 20px; font-weight: 700; color: var(--accent); }

.site-footer { border-top: 1px solid var(--line); padding: 34px 0; }
.footer-shell { display: flex; justify-content: space-between; gap: 30px; align-items: end; color: var(--muted); font-size: 12px; }
.footer-shell strong { color: var(--text); font-size: 14px; }
.footer-shell p { margin: 4px 0 0; }

/* Blog / content pages */
.content-page { width: min(calc(100% - 48px), 780px); margin: 0 auto; padding: 96px 0 120px; }
.content-page h1 { font-size: clamp(40px, 6vw, 64px); letter-spacing: -.05em; line-height: 1.05; margin: 0 0 18px; }
.content-page .lead { color: var(--muted); font-size: 18px; margin-bottom: 50px; }
.post-list-clean { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--text); }
.post-list-clean li { padding: 20px 0; border-bottom: 1px solid var(--line); }
.post-list-clean time { display: block; font-size: 12px; color: var(--muted); margin-bottom: 4px; }
.post-list-clean a { font-weight: 600; }
.post { width: min(calc(100% - 48px), 780px); margin: 0 auto; padding: 96px 0 120px; }
.post-title { font-size: clamp(34px, 5vw, 54px); line-height: 1.12; letter-spacing: -.04em; }
.post-meta { color: var(--muted); font-size: 13px; }
.post-content h2, .post-content h3 { margin-top: 42px; line-height: 1.3; }
.post-content img { border-radius: 10px; }
.post-content pre { overflow: auto; background: #f4f5f6; border: 1px solid var(--line); padding: 16px; border-radius: 10px; }

@media (max-width: 900px) {
  .nav-shell { grid-template-columns: 1fr auto; min-height: 66px; }
  .site-nav { grid-column: 1 / -1; order: 3; justify-content: flex-start; overflow-x: auto; padding-bottom: 12px; gap: 18px; }
  .language-switch { border-left: 0; padding-left: 0; }
  .hero { padding-top: 80px; }
  .intro { grid-template-columns: 1fr; gap: 28px; }
  .section-heading-row, .contact-grid { grid-template-columns: 1fr; gap: 28px; }
  .research-grid { grid-template-columns: 1fr; }
  .teaching-grid { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .shell { width: min(calc(100% - 32px), var(--max)); }
  .hero { padding: 64px 0 72px; }
  .hero h1 { font-size: 52px; }
  .name-ko { display: block; margin: 16px 0 0; font-size: 22px; vertical-align: 0; }
  .hero-statement { font-size: 21px; }
  .text-link { margin-left: 0; }
  .section { padding: 76px 0; }
  .large-prose > p { font-size: 18px; }
  .facts > div { grid-template-columns: 1fr; gap: 4px; }
  .research-card { min-height: 0; padding: 26px; }
  .card-index { margin-bottom: 38px; }
  .publication { grid-template-columns: 55px 1fr; gap: 14px; }
  .pub-venue { grid-column: 2; text-align: left; }
  .footer-shell { align-items: flex-start; flex-direction: column; }
  .content-page, .post { width: min(calc(100% - 32px), 780px); padding-top: 64px; }
}

/* Accessible text for icon-only controls */
.sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

/* Flag language switch */
.language-switch {
  gap: 8px;
}
.language-switch button {
  width: 38px;
  height: 30px;
  padding: 4px;
  border: 1px solid transparent;
  border-radius: 8px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  opacity: .55;
  transition: opacity .16s ease, border-color .16s ease, background .16s ease, transform .16s ease;
}
.language-switch button:hover {
  opacity: .9;
  transform: translateY(-1px);
}
.language-switch button.active {
  opacity: 1;
  border-color: #cfd4da;
  background: #f7f8f9;
}
.language-switch img {
  width: 28px;
  height: 19px;
  display: block;
  object-fit: cover;
  border-radius: 2px;
  box-shadow: 0 0 0 1px rgba(0,0,0,.08);
}

/* HAS Lab */
.lab-hero { padding: 102px 0 84px; }
.lab-title-row {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(260px, .6fr);
  gap: 72px;
  align-items: end;
  margin-top: 18px;
}
.lab-title-row h1 {
  margin: 0;
  font-size: clamp(58px, 9vw, 104px);
  line-height: .95;
  letter-spacing: -.07em;
}
.lab-title-full {
  display: block;
  margin-top: 18px;
  color: #80868e;
  font-size: .24em;
  line-height: 1.2;
  letter-spacing: -.025em;
  font-weight: 600;
}
.lab-lead {
  margin: 34px 0 0;
  max-width: 760px;
  color: #444a51;
  font-size: clamp(20px, 2.7vw, 27px);
  line-height: 1.5;
  letter-spacing: -.02em;
}
.lab-meta {
  padding-left: 24px;
  border-left: 1px solid var(--line);
  display: flex;
  flex-direction: column;
  gap: 6px;
  color: var(--muted);
  font-size: 13px;
}
.lab-meta strong { color: var(--text); font-size: 16px; }
.lab-focus-tags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 46px; }
.lab-focus-tags span {
  padding: 7px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: #565c64;
  font-size: 12px;
  font-weight: 600;
}
.lab-section-head {
  display: grid;
  grid-template-columns: minmax(300px, .85fr) minmax(300px, 1.15fr);
  gap: 72px;
  align-items: end;
  margin-bottom: 42px;
}
.lab-section-head h2 { margin: 10px 0 0; font-size: clamp(34px, 5vw, 50px); line-height: 1.08; letter-spacing: -.045em; }
.lab-section-head > p { margin: 0; max-width: 620px; color: var(--muted); font-size: 16px; }
.member-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; }
.member-card {
  scroll-margin-top: 96px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px;
  background: #fff;
  transition: border-color .18s ease, box-shadow .18s ease;
}
.member-card:target { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.member-topline { min-height: 28px; display: flex; justify-content: space-between; gap: 16px; align-items: center; }
.member-status {
  display: inline-flex;
  padding: 5px 9px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: .04em;
  text-transform: uppercase;
}
.member-period { color: var(--muted); font-size: 12px; }
.member-card h3 { margin: 26px 0 4px; font-size: 25px; line-height: 1.2; letter-spacing: -.03em; }
.member-program { margin: 0 0 24px; color: var(--muted); font-size: 13px; }
.member-detail { display: grid; grid-template-columns: 125px 1fr; gap: 12px; padding: 11px 0; border-top: 1px solid #edf0f2; font-size: 13px; }
.member-detail-label { color: var(--muted); font-size: 11px; font-weight: 700; letter-spacing: .025em; text-transform: uppercase; }
.member-interests { display: flex; flex-wrap: wrap; gap: 7px; margin-top: 20px; }
.member-interests span { padding: 5px 9px; border-radius: 999px; background: var(--surface); color: #666d75; font-size: 11px; font-weight: 600; }
.member-papers { margin-top: 24px; padding-top: 18px; border-top: 1px solid var(--line); }
.member-papers > a { display: grid; grid-template-columns: 95px 1fr; gap: 12px; padding: 9px 0; font-size: 12px; line-height: 1.45; }
.member-papers > a span { color: var(--accent); font-weight: 700; }
.empty-state {
  padding: 56px 28px;
  border: 1px dashed #cfd4da;
  border-radius: var(--radius);
  color: #7c838b;
  text-align: center;
  background: #fafbfb;
}
.empty-state.compact { padding: 36px 24px; }
.lab-publication-list { border-top: 1px solid var(--text); }
.lab-publication {
  scroll-margin-top: 96px;
  display: grid;
  grid-template-columns: 72px 1fr 100px;
  gap: 30px;
  align-items: start;
  padding: 24px 0 26px;
  border-bottom: 1px solid #d9dde1;
}
.lab-publication:target { background: rgba(234,241,255,.5); }
.lab-pub-year { font-size: 14px; font-weight: 700; }
.lab-pub-main h3 { margin: 0 0 7px; font-size: 17px; line-height: 1.5; letter-spacing: -.012em; }
.lab-pub-main > p { margin: 0; color: var(--muted); font-size: 13px; }
.lab-pub-venue { color: var(--accent); text-align: right; font-size: 12px; font-weight: 700; }
.paper-member-links { display: flex; flex-wrap: wrap; gap: 7px; align-items: center; margin-top: 13px; }
.paper-member-label { color: var(--muted); font-size: 10px; font-weight: 700; letter-spacing: .04em; text-transform: uppercase; margin-right: 3px; }
.paper-member-links a { padding: 4px 8px; border-radius: 999px; background: white; border: 1px solid #dce1e6; color: #4d555e; font-size: 11px; font-weight: 600; }
.alumni-list { border-top: 1px solid var(--text); }
.alumni-row {
  scroll-margin-top: 96px;
  display: grid;
  grid-template-columns: 1fr 120px minmax(150px, .45fr);
  gap: 28px;
  align-items: center;
  padding: 19px 0;
  border-bottom: 1px solid var(--line);
}
.alumni-row:target { background: var(--accent-soft); }
.alumni-row h3 { margin: 0 0 3px; font-size: 16px; }
.alumni-row p, .alumni-period, .alumni-next { margin: 0; color: var(--muted); font-size: 12px; }
.alumni-next { text-align: right; }

@media (max-width: 900px) {
  .lab-title-row, .lab-section-head { grid-template-columns: 1fr; gap: 28px; }
  .lab-meta { padding-left: 0; padding-top: 18px; border-left: 0; border-top: 1px solid var(--line); }
  .member-grid { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .lab-hero { padding: 64px 0 62px; }
  .lab-title-row h1 { font-size: 60px; }
  .lab-title-full { font-size: 18px; }
  .lab-lead { font-size: 20px; }
  .lab-publication { grid-template-columns: 54px 1fr; gap: 14px; }
  .lab-pub-venue { grid-column: 2; text-align: left; }
  .member-detail { grid-template-columns: 1fr; gap: 3px; }
  .member-papers > a { grid-template-columns: 1fr; gap: 2px; }
  .alumni-row { grid-template-columns: 1fr; gap: 5px; }
  .alumni-next { text-align: left; }
}