:root {
  color-scheme: light;
  --ink: #18333b;
  --ink-soft: #4d6268;
  --muted: #74858a;
  --line: #d9e1df;
  --paper: #f7f8f6;
  --white: #fff;
  --mint: #a8cbb1;
  --mint-soft: #e8f0e9;
  --deep: #143840;
  --display: Georgia, 'Times New Roman', serif;
  --sans: -apple-system, BlinkMacSystemFont, 'Apple SD Gothic Neo', 'Malgun Gothic', 'Segoe UI', sans-serif;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 88px; }
body { margin: 0; background: var(--paper); color: var(--ink); font-family: var(--sans); -webkit-font-smoothing: antialiased; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; text-decoration: none; }
button { font: inherit; }
img, svg { display: block; }
::selection { background: var(--mint); color: var(--deep); }
.container { width: min(100% - 80px, 1240px); margin-inline: auto; }
html[lang='ko'] .en, html[lang='en'] .ko { display: none !important; }
:focus-visible { outline: 3px solid #427c69; outline-offset: 4px; }
.skip-link { position: fixed; z-index: 100; top: 10px; left: 10px; padding: 12px 18px; transform: translateY(-150%); background: var(--deep); color: white; border-radius: 4px; }
.skip-link:focus { transform: translateY(0); }

.site-header { position: sticky; z-index: 20; top: 0; height: 79px; border-bottom: 1px solid rgba(24, 51, 59, .09); background: rgba(247, 248, 246, .93); backdrop-filter: blur(18px); }
.header-inner { height: 100%; display: flex; align-items: center; gap: 40px; }
.home-link { flex: 0 0 auto; color: var(--deep); font-family: var(--display); font-size: 16px; font-weight: 700; }
.site-nav { display: flex; gap: clamp(18px, 2.9vw, 42px); align-items: center; margin-inline: auto; }
.site-nav a { color: var(--ink-soft); font-size: 13px; font-weight: 600; transition: color .2s; white-space: nowrap; }
.home-link:hover, .site-nav a:hover, .site-footer a:hover { color: #39715c; }
.language-switch { display: flex; align-items: center; gap: 7px; flex: 0 0 auto; color: #a0aaa7; font-size: 11px; }
.language-switch button { border: 0; background: none; color: #93a19c; font-size: 11px; font-weight: 750; letter-spacing: .1em; cursor: pointer; padding: 6px 2px; }
.language-switch button[aria-pressed='true'] { color: var(--deep); }

.hero { background: var(--paper); }
.hero-grid { border-bottom: 1px solid var(--line); }
.hero-copy { max-width: 790px; padding: 80px 0 88px; }
.hero h1 { display: flex; align-items: baseline; flex-wrap: wrap; gap: 12px; margin: 0; font-size: 22px; letter-spacing: -.04em; line-height: 1.35; font-weight: 700; }
html[lang='en'] .hero h1 { font-family: var(--display); font-weight: 600; letter-spacing: -.025em; }
.degree-label { color: #5e8b70; font-family: var(--display); font-size: 15px; font-weight: 600; letter-spacing: 0; }
.hero-email { display: inline-flex; align-items: center; gap: 10px; margin-top: 12px; padding-bottom: 5px; border-bottom: 1px solid #8caaa0; color: #497a65; font-family: var(--display); font-size: 20px; }
.hero-email:hover { color: var(--deep); }
.hero-email span { font-family: var(--sans); font-size: 15px; }
.hero-description { max-width: 670px; margin: 35px 0 0; color: var(--ink-soft); font-size: 15px; line-height: 1.9; word-break: keep-all; }

.section { padding: 118px 0; }
.section-grid { display: grid; grid-template-columns: minmax(220px, 31%) minmax(0, 1fr); gap: 6%; }
.section-index { margin: 0 0 18px; color: #6b9a81; font-size: 11px; font-weight: 800; letter-spacing: .18em; }
.section h2 { margin: 0; color: var(--deep); font-size: clamp(34px, 3.4vw, 48px); font-weight: 650; letter-spacing: -.065em; line-height: 1.25; }
html[lang='en'] .section h2 { font-family: var(--display); font-weight: 600; letter-spacing: -.055em; }
.section-body { max-width: 790px; }
.section-body > p { margin: 18px 0 0; color: var(--ink-soft); font-size: 15px; line-height: 2; word-break: keep-all; }
.section-body > p:first-child { margin-top: 0; }
.about-facts { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; margin-top: 36px; padding-top: 27px; border-top: 1px solid var(--line); }
.about-facts > div { display: flex; flex-direction: column; gap: 10px; }
.fact-label { color: #83a38e; font-size: 10px; font-weight: 800; letter-spacing: .11em; }
.about-facts strong { font-size: 13px; font-weight: 650; line-height: 1.5; }

.research-section { background: #edf2ee; }
.section-top { display: flex; align-items: end; justify-content: space-between; gap: 50px; margin-bottom: 48px; }
.research-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 14px; }
.research-card { min-height: 300px; padding: 27px 24px 30px; background: rgba(255,255,255,.9); border: 1px solid #e3eae4; transition: transform .25s, box-shadow .25s; }
.research-card:hover { transform: translateY(-4px); box-shadow: 0 20px 35px rgba(34, 74, 56, .07); }
.card-number { color: #92aa9a; font-family: var(--display); font-size: 13px; }
.research-icon { display: grid; place-items: center; width: 54px; height: 54px; margin-top: 30px; border-radius: 50%; background: #e8f1e9; color: #4f806b; }
.research-icon svg { width: 28px; height: 28px; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }
.research-card h3 { margin: 25px 0 11px; color: var(--deep); font-size: 16px; font-weight: 700; letter-spacing: -.04em; line-height: 1.45; word-break: keep-all; }
html[lang='en'] .research-card h3 { font-size: 16px; letter-spacing: -.02em; }
.research-card p { margin: 0; color: #667a73; font-size: 12px; line-height: 1.85; word-break: keep-all; }

.publications-section { background: #fff; }
.publication-list { border-top: 2px solid var(--deep); }
.publication { display: grid; grid-template-columns: 78px minmax(0, 1fr) 64px; gap: 28px; padding: 29px 0 30px; border-bottom: 1px solid #e2e8e5; }
.publication-year { padding-top: 4px; color: #65907a; font-family: var(--display); font-size: 17px; }
.publication-meta { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin: 0 0 9px; color: #7d9688; font-size: 11px; font-weight: 750; line-height: 1.6; }
.role-tag { padding: 3px 7px; border-radius: 3px; background: #eaf2e9; color: #49735d; font-size: 10px; white-space: nowrap; }
.publication h3 { max-width: 900px; margin: 0; color: var(--deep); font-size: 17px; font-weight: 670; letter-spacing: -.02em; line-height: 1.48; }
.publication-authors { margin: 10px 0 0; color: #7e8e8a; font-size: 12px; line-height: 1.6; }
.publication-authors strong { color: var(--deep); font-weight: 700; }
.publication-summary { margin: 13px 0 0; color: #5e706d; font-size: 12px; line-height: 1.7; word-break: keep-all; }
.doi-link { display: flex; align-items: start; justify-content: end; gap: 7px; padding-top: 5px; color: #4f8068; font-size: 11px; font-weight: 800; letter-spacing: .05em; white-space: nowrap; }
.doi-link:hover { color: var(--deep); text-decoration: underline; text-underline-offset: 3px; }
.doi-link span { font-size: 15px; font-weight: 400; }

.experience-section { background: var(--paper); }
.timeline { border-top: 2px solid var(--deep); }
.timeline-item { display: grid; grid-template-columns: 155px minmax(0, 1fr); gap: 25px; padding: 28px 0 30px; border-bottom: 1px solid var(--line); }
.timeline-date { padding-top: 3px; color: #69907b; font-family: var(--display); font-size: 14px; white-space: nowrap; }
.timeline h3 { margin: 0 0 6px; color: var(--deep); font-size: 17px; font-weight: 680; letter-spacing: -.035em; }
.timeline p { margin: 0; color: var(--ink-soft); font-size: 13px; line-height: 1.7; }
.timeline .timeline-detail { margin-top: 10px; color: #85928e; font-size: 11px; }
.site-footer { min-height: 78px; background: #102c33; color: #93a9a8; }
.footer-inner { min-height: 78px; display: flex; align-items: center; justify-content: space-between; gap: 20px; font-size: 11px; }
.site-footer a { color: #bdd4cf; white-space: nowrap; }

@media (max-width: 1060px) {
  .container { width: min(100% - 56px, 1240px); }
  .header-inner { gap: 24px; }
  .research-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .research-card { min-height: 255px; }
}

@media (max-width: 720px) {
  html { scroll-padding-top: 68px; }
  .container { width: min(100% - 36px, 1240px); }
  .site-header { height: auto; min-height: 67px; }
  .header-inner { min-height: 67px; flex-wrap: wrap; column-gap: 12px; row-gap: 0; justify-content: space-between; }
  .home-link { font-size: 15px; }
  .site-nav { order: 3; width: 100%; margin: 0; min-height: 40px; justify-content: space-between; gap: 10px; }
  .site-nav a { font-size: 11px; }
  .hero-copy { padding: 58px 0 68px; }
  .hero h1 { font-size: 20px; }
  .hero-email { font-size: 18px; }
  .hero-description { font-size: 14px; }
  .section { padding: 78px 0; }
  .section-grid { grid-template-columns: 1fr; gap: 34px; }
  .section-top { align-items: start; flex-direction: column; gap: 14px; margin-bottom: 30px; }
  .publication { grid-template-columns: 48px minmax(0, 1fr); gap: 12px; padding: 23px 0; }
  .publication h3 { font-size: 15px; }
  .doi-link { grid-column: 2; justify-content: start; padding-top: 0; }
  .footer-inner { flex-wrap: wrap; justify-content: space-between; padding-block: 20px; }
  .footer-inner > span:nth-child(2) { order: 3; width: 100%; }
}

@media (max-width: 440px) {
  .about-facts { grid-template-columns: 1fr; gap: 18px; }
  .research-grid { grid-template-columns: 1fr; }
  .research-card { min-height: 0; padding: 24px; }
  .research-icon { margin-top: 17px; }
  .research-card h3 { margin-top: 18px; }
  .timeline-item { grid-template-columns: 1fr; gap: 9px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: .01ms !important; animation-duration: .01ms !important; }
}