/* =========================================================
   Kyongsik Yun, Ph.D. — yunks128.github.io
   Technical, professional, responsive.
   ========================================================= */

:root {
  --bg: #fafafa;
  --bg-alt: #f0f2f5;
  --surface: #ffffff;
  --ink: #0b1220;
  --ink-2: #2a3142;
  --ink-soft: #5a6272;
  --rule: #e3e6eb;
  --rule-strong: #c9cfd8;
  --accent: #0b4f9c;
  --accent-2: #0e7490;
  --mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --max: 1120px;
  --gutter: clamp(1rem, 4vw, 2rem);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0e13;
    --bg-alt: #0f141c;
    --surface: #131924;
    --ink: #e8ecf3;
    --ink-2: #c6ccd7;
    --ink-soft: #8a93a3;
    --rule: #1e2633;
    --rule-strong: #2a3342;
    --accent: #5aa7ff;
    --accent-2: #4fd1c5;
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--sans);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.65;
  font-size: 16px;
  font-feature-settings: "ss01", "cv11", "kern";
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.container {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

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

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color .15s ease, color .15s ease;
}

a:hover { border-bottom-color: currentColor; }

/* ---------- Eyebrows / section labels ---------- */
.eyebrow {
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
  margin: 0 0 1.25rem;
}
.eyebrow span { color: var(--accent); font-weight: 500; }
.eyebrow.small { font-size: 0.7rem; margin-bottom: 0.75rem; }

/* ---------- Headings ---------- */
h1, h2, h3 { font-weight: 600; letter-spacing: -0.015em; color: var(--ink); }
h2 {
  font-size: clamp(1.5rem, 2.6vw, 2rem);
  margin: 0 0 2rem;
  max-width: 36ch;
  line-height: 1.25;
}
h3 {
  font-size: 1.1rem;
  margin: 0 0 0.5rem;
}

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--rule);
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 0.85rem 0;
  flex-wrap: wrap;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--ink);
  border-bottom: none;
  font-weight: 600;
}
.brand-mark {
  display: inline-grid;
  place-items: center;
  width: 1.85rem;
  height: 1.85rem;
  border-radius: 6px;
  background: var(--ink);
  color: var(--bg);
  font-family: var(--mono);
  font-weight: 500;
  font-size: 0.78rem;
  letter-spacing: 0.02em;
}
.brand-name { font-size: 0.98rem; }

.nav { display: flex; gap: 0.25rem; flex-wrap: wrap; }
.nav a {
  color: var(--ink-2);
  font-size: 0.92rem;
  font-weight: 500;
  padding: 0.35rem 0.7rem;
  border-radius: 6px;
  border-bottom: none;
}
.nav a:hover { color: var(--ink); background: var(--bg-alt); }

/* ---------- Hero ---------- */
.hero { padding: clamp(3rem, 7vw, 5.5rem) 0 clamp(2.5rem, 5vw, 4rem); }

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr);
  gap: clamp(1.5rem, 4vw, 3rem);
  align-items: start;
}

.hero-text .lead {
  font-size: clamp(1.05rem, 1.25vw, 1.2rem);
  color: var(--ink);
  margin: 0 0 1.1rem;
  line-height: 1.55;
}
.hero-text p { margin: 0 0 1.1rem; color: var(--ink-2); }

.hero-portrait {
  position: relative;
  border: 1px solid var(--rule);
  border-radius: 10px;
  overflow: hidden;
  background: var(--surface);
  aspect-ratio: 4 / 5;
  box-shadow: 0 1px 2px rgba(0,0,0,0.04), 0 20px 40px -20px rgba(0,0,0,0.12);
}
.hero-portrait img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center top;
}

/* ---------- Meta list ---------- */
.meta-list {
  list-style: none;
  padding: 1.25rem 0 0;
  margin: 1.25rem 0 0;
  border-top: 1px solid var(--rule);
  display: grid;
  gap: 0.55rem;
  font-size: 0.94rem;
}
.meta-list li {
  display: grid;
  grid-template-columns: 9rem 1fr;
  gap: 1rem;
  align-items: baseline;
}
.meta-k {
  font-family: var(--mono);
  font-size: 0.76rem;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--ink-soft);
}
.meta-v { color: var(--ink-2); }

/* ---------- Sections ---------- */
.section {
  padding: clamp(3rem, 6vw, 5rem) 0;
  border-top: 1px solid var(--rule);
}
.section-alt { background: var(--bg-alt); }

/* ---------- Research Focus grid ---------- */
.focus-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1rem;
  margin-bottom: 2.5rem;
}
.focus-card {
  background: var(--surface);
  border: 1px solid var(--rule);
  border-radius: 10px;
  padding: 1.25rem;
  transition: transform .15s ease, border-color .15s ease, box-shadow .15s ease;
}
.focus-card:hover {
  transform: translateY(-2px);
  border-color: var(--rule-strong);
  box-shadow: 0 6px 20px -10px rgba(0,0,0,0.12);
}
.focus-card h3 { margin-bottom: 0.6rem; }
.focus-card p { margin: 0; color: var(--ink-2); font-size: 0.95rem; }

/* ---------- Awards ---------- */
.awards {
  border-top: 1px solid var(--rule);
  padding-top: 2rem;
}
.awards-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0.6rem;
}
.awards-list li {
  display: grid;
  grid-template-columns: 4rem 1fr;
  gap: 1rem;
  align-items: baseline;
  padding: 0.4rem 0;
  border-bottom: 1px dashed var(--rule);
  color: var(--ink-2);
  font-size: 0.95rem;
}
.awards-list li:last-child { border-bottom: none; }
.awards-list .year {
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--accent);
  font-weight: 500;
}

/* ---------- News grid ---------- */
.news-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem;
}
.news-card {
  background: var(--surface);
  border: 1px solid var(--rule);
  border-radius: 10px;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: transform .15s ease, border-color .15s ease, box-shadow .15s ease;
}
.news-card:hover {
  transform: translateY(-2px);
  border-color: var(--rule-strong);
  box-shadow: 0 10px 30px -14px rgba(0,0,0,0.18);
}
.news-thumb {
  aspect-ratio: 16 / 9;
  background: var(--bg-alt);
  overflow: hidden;
}
.news-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.news-body { padding: 1rem 1.1rem 1.25rem; }
.news-body h3 { margin: 0 0 0.4rem; font-size: 1rem; }
.news-body p { margin: 0; color: var(--ink-soft); font-size: 0.92rem; line-height: 1.55; }

/* ---------- Projects ---------- */
.project {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 2fr);
  gap: clamp(1rem, 3vw, 2rem);
  padding: 2rem 0;
  border-bottom: 1px solid var(--rule);
  align-items: start;
}
.project:last-child { border-bottom: none; }
.project-head { position: sticky; top: 5rem; }
.project-head h3 {
  font-size: 1.15rem;
  margin: 0 0 0.35rem;
}
.project-sub {
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.04em;
  color: var(--ink-soft);
  margin: 0 0 1rem;
}
.project-img {
  margin-top: 0.75rem;
  width: 100%;
  border-radius: 8px;
  border: 1px solid var(--rule);
  aspect-ratio: 16 / 9;
  object-fit: cover;
  background: var(--bg-alt);
}
.pub-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0.8rem;
}
.pub-list li {
  position: relative;
  padding-left: 1.2rem;
  font-size: 0.95rem;
  color: var(--ink-2);
  line-height: 1.6;
}
.pub-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.7rem;
  width: 6px;
  height: 1px;
  background: var(--accent);
}
.pub-list em { color: var(--ink); font-style: italic; }
.pub-list a { color: var(--accent); text-decoration: none; border-bottom: 1px solid transparent; transition: border-color 0.15s; }
.pub-list a:hover { border-bottom-color: var(--accent); }
.pub-note {
  font-size: 0.95rem;
  color: var(--ink-2);
  margin: 0 0 2rem;
  padding: 0.8rem 1rem;
  border-left: 2px solid var(--accent);
  background: var(--bg-alt);
}
.pub-note a { color: var(--accent); }

/* ---------- Outreach ---------- */
.outreach-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
}
.outreach-grid h3 { margin-bottom: 0.6rem; }
.outreach-grid p { margin: 0; color: var(--ink-2); font-size: 0.95rem; }

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--rule);
  padding: 2rem 0;
  color: var(--ink-soft);
  font-size: 0.88rem;
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.footer-inner p { margin: 0; }
.footer-meta { font-family: var(--mono); font-size: 0.78rem; }

/* ---------- Responsive ---------- */
@media (max-width: 900px) {
  .hero-grid { grid-template-columns: 1fr; }
  .hero-portrait { max-width: 340px; aspect-ratio: 1 / 1.1; }
  .project { grid-template-columns: 1fr; }
  .project-head { position: static; }
  .meta-list li { grid-template-columns: 7rem 1fr; }
}

@media (max-width: 600px) {
  .header-inner { gap: 0.5rem; }
  .brand-name { display: none; }
  .nav a { padding: 0.3rem 0.55rem; font-size: 0.88rem; }
  .meta-list li { grid-template-columns: 1fr; gap: 0.15rem; }
  .awards-list li { grid-template-columns: 3.5rem 1fr; }
  h2 { max-width: none; }
}

/* ---------- A11y ---------- */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; scroll-behavior: auto !important; }
}