/* ── RESET & VARIABLES ──────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --white:          #ffffff;
  --crimson-pale:   #f8eef0;     /* light KU crimson for alt sections  */
  --crimson:        #A41E34;     /* KU crimson                          */
  --crimson-dark:   #7d1628;     /* hover                               */
  --crimson-soft:   #c8687a;     /* muted crimson for prof links        */
  --crimson-muted:  rgba(164, 30, 52, 0.10);
  --ucla:           #2774AE;     /* UCLA blue                           */
  --ucla-dark:      #1a5a8e;     /* UCLA blue hover                     */
  --ucla-soft:      #6aaad6;     /* muted UCLA blue for prof links      */
  --ink:            #1a1a1a;
  --ink-soft:       #4a4a52;
  --ink-light:      #8a8a92;
  --border:         #e6d5d8;
  --border-pale:    #f0e4e7;
  --font:           'Roboto', system-ui, -apple-system, sans-serif;
  --font-display:   'Montserrat', system-ui, sans-serif;
  --nav-h:          62px;
  --max-w:          1140px;
  --radius:         10px;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  font-size: 15.5px;
  line-height: 1.7;
  color: var(--ink);
  background: var(--white);
  -webkit-font-smoothing: antialiased;
}

a { color: var(--crimson); text-decoration: none; }
a:hover { text-decoration: underline; }
img { display: block; max-width: 100%; }
ul { list-style: none; padding: 0; }


/* ── NAVBAR ──────────────────────────────────────── */
#navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-h);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-pale);
  z-index: 200;
  transition: box-shadow 0.3s;
}
#navbar.scrolled { box-shadow: 0 2px 18px rgba(164, 30, 52, 0.08); }

.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 15px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  font-size: 18px;
  font-weight: 700;
  color: var(--ink);
  letter-spacing: 0.01em;
}
.nav-brand:hover { text-decoration: none; color: var(--crimson); }

#nav-menu {
  display: flex;
  gap: 28px;
  list-style: none;
}
#nav-menu a {
  font-size: 14px;
  font-weight: 500;
  color: var(--ink-soft);
  letter-spacing: 0.03em;
  transition: color 0.18s;
}
#nav-menu a:hover,
#nav-menu a.active { color: var(--crimson); text-decoration: none; }

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--ink);
  font-size: 20px;
  cursor: pointer;
  padding: 6px;
}


/* ── LAYOUT HELPERS ──────────────────────────────── */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 15px;
}

.sec {
  padding: 24px 0;
}
.sec-white  { background: var(--white); }
.sec-crimson { background: var(--crimson-pale); }

/* First section needs top padding for navbar */
#about { padding-top: calc(var(--nav-h) + 30px); }


/* ── SECTION HEADINGS ────────────────────────────── */
.sec-heading {
  font-size: 26px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 24px;
  position: relative;
  padding-bottom: 10px;
}
.sec-heading::after {
  content: '';
  position: absolute;
  bottom: 0; left: 0;
  width: 44px; height: 3px;
  background: var(--crimson);
  border-radius: 2px;
}

.subsec-heading {
  font-size: 18px;
  font-weight: 600;
  color: var(--ink);
  margin: 28px 0 10px;
}
.subsec-heading:first-of-type { margin-top: 0; }

.subsec-title {
  font-size: 17px;
  font-weight: 600;
  color: var(--ink);
  margin-bottom: 12px;
}


/* ── BIO / ABOUT ─────────────────────────────────── */
.bio-grid {
  display: grid;
  grid-template-columns: 1fr 2fr;   /* col-4 / col-8 like Woojung Han */
  gap: 30px;
  align-items: start;
}

/* Left column */
.bio-left {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 10px;
  gap: 0;
}

.avatar-wrap {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  overflow: hidden;
  border: 3px solid var(--border-pale);
  box-shadow: 0 6px 24px rgba(164, 30, 52, 0.10);
  flex-shrink: 0;
}
.avatar {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.4s ease;
}
.avatar-wrap:hover .avatar { transform: scale(1.04); }

.identity { text-align: center; }

.identity-name {
  font-family: var(--font-display);
  font-size: 1.75em;           /* Woojung Han: 1.75em */
  font-weight: 300;
  color: #000;
  margin: 20px 0 10px 0;      /* Woojung Han: margin: 20px 0 10px 0 */
}
.identity-title {
  font-family: var(--font-display);
  font-size: 1rem;             /* Woojung Han: 1rem */
  font-weight: 300;
  color: rgba(0,0,0,0.68);
  margin: 0 0 10px 0;
}
.identity-lab {
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 300;
  margin: 0 0 10px 0;
}
.identity-lab a {
  color: rgba(0,0,0,0.68);
  font-weight: 300;
}
.ku-color   { color: var(--crimson); font-weight: 400; }
.ucla-color { color: var(--ucla);    font-weight: 400; }
.identity-lab-link { color: rgba(0,0,0,0.68); font-weight: 300; }

.identity-extra {
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 300;
  color: rgba(0,0,0,0.68);
  margin: 0 0 10px 0;
}

/* Institution / person link colors */
.link-ku       { color: var(--crimson) !important; }
.link-ku:hover { color: var(--crimson-dark) !important; }
.link-ku-prof       { color: var(--crimson-soft) !important; }
.link-ku-prof:hover { color: var(--crimson) !important; }
.link-ucla       { color: var(--ucla) !important; }
.link-ucla:hover { color: var(--ucla-dark) !important; }
.link-ucla-prof       { color: var(--ucla-soft) !important; }
.link-ucla-prof:hover { color: var(--ucla) !important; }

/* UCLA-colored text (for identity-extra) */
.text-ucla { color: var(--ucla); font-weight: 600; }

.social-links {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
  justify-content: center;
  font-family: var(--font-display);
  font-size: 14px;
  font-weight: 400;
  margin-top: 4px;
}
.social-links a {
  color: var(--ink);
  transition: color 0.18s;
}
.social-links a:hover { color: var(--ink-soft); text-decoration: none; }
.social-links .fa-github,
.social-links .fa-linkedin { font-size: 18px; }
.sep { color: var(--ink-light); user-select: none; }

/* Right column */
.bio-right {}

.bio-text {
  color: var(--ink);
  line-height: 1.75;
  margin-bottom: 16px;
}
.bio-text a { color: var(--crimson); }
.bio-text a:hover { color: var(--crimson-dark); }

.research-interests {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 24px;
}
.interest-tag {
  display: inline-block;
  font-size: 12.5px;
  font-weight: 500;
  padding: 5px 14px;
  border-radius: 20px;
  background: rgba(164, 30, 52, 0.10);
  color: var(--crimson);
  letter-spacing: 0.01em;
}

.contact-edu-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
  margin-top: 28px;
}

/* Contact list */
.info-list {
  list-style: none;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.info-list li {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: 14.5px;
  color: var(--ink-soft);
}
.fa-li-icon {
  color: var(--ink);
  margin-top: 3px;
  width: 16px;
  flex-shrink: 0;
}

/* Education list */
.edu-list {
  list-style: none;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.edu-list li {
  display: flex;
  align-items: flex-start;
  gap: 10px;
}
.edu-icon {
  color: var(--ink);
  margin-top: 4px;
  flex-shrink: 0;
}
.edu-degree {
  font-size: 14.5px;
  font-weight: 500;
  color: var(--ink);
}
.edu-school {
  font-size: 13px;
  color: var(--ink-light);
  margin-top: 2px;
}


/* ── NEWS ────────────────────────────────────────── */
.news-list {
  list-style: none;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.news-list li {
  font-size: 15px;
  color: var(--ink);
  padding-left: 4px;
  border-left: 3px solid transparent;
  padding-left: 12px;
  transition: border-color 0.2s;
}
.news-list li:hover { border-left-color: var(--crimson); }
.news-date {
  font-weight: 600;
  color: var(--crimson);
  margin-right: 6px;
}


/* ── PROJECTS GRID ───────────────────────────────── */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 24px;
}

.project-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  cursor: pointer;
  text-decoration: none;
  color: inherit;
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}
.project-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 12px 32px rgba(164, 30, 52, 0.12);
  border-color: var(--crimson);
  text-decoration: none;
  color: inherit;
}

.project-thumb {
  width: 100%;
  height: 190px;
  overflow: hidden;
  background: var(--crimson-pale);
  flex-shrink: 0;
}
.project-thumb img,
.project-thumb video {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.4s ease;
}
.project-card:hover .project-thumb img,
.project-card:hover .project-thumb video { transform: scale(1.06); }

.project-body {
  padding: 20px 22px 18px;
  display: flex;
  flex-direction: column;
  flex: 1;
}
.project-top { flex: 1; }

.project-tag {
  display: inline-block;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--crimson);
  background: var(--crimson-muted);
  padding: 3px 9px;
  border-radius: 20px;
  margin-bottom: 10px;
}
.project-card h3 {
  font-size: 16px;
  font-weight: 600;
  color: var(--ink);
  line-height: 1.3;
  margin-bottom: 8px;
}
.project-card p {
  font-size: 13.5px;
  color: var(--ink-soft);
  line-height: 1.7;
}

.project-footer {
  margin-top: 16px;
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  font-weight: 600;
  color: var(--crimson);
}
.project-footer svg { flex-shrink: 0; }


/* ── PUBLICATIONS ────────────────────────────────── */

/* Filter toggle */
.pub-filter {
  position: relative;
  margin: 0 0 28px 0;
  display: inline-flex;
  gap: 4px;
  padding: 5px;
  background: #edd8dc;
  border-radius: 12px;
  box-shadow: inset 0 1px 3px rgba(0,0,0,0.07);
}
.filter-slider {
  position: absolute;
  top: 5px; left: 5px;
  height: calc(100% - 10px);
  width: 0;
  background: var(--white);
  border-radius: 8px;
  box-shadow: 0 2px 6px rgba(164,30,52,0.12);
  transition: left 0.32s cubic-bezier(0.4,0,0.2,1), width 0.32s cubic-bezier(0.4,0,0.2,1);
  z-index: 0;
  pointer-events: none;
}
.pub-filter-btn {
  position: relative;
  z-index: 1;
  padding: 7px 20px;
  border: none;
  background: transparent;
  font-size: 14px;
  font-weight: 600;
  color: var(--ink-soft);
  border-radius: 8px;
  cursor: pointer;
  transition: color 0.18s;
  letter-spacing: 0.02em;
  font-family: var(--font);
}
.pub-filter-btn:hover { color: var(--ink); }
.pub-filter-btn.active { color: var(--crimson); }

/* Paper list */
.ul-papers {
  list-style: none;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0;
}
.ul-papers > li {
  display: flex;
  gap: 22px;
  align-items: flex-start;
  padding: 22px 0;
  border-bottom: 1px solid var(--border-pale);
}
.ul-papers > li:last-child { border-bottom: none; }

/* Publication figure with hover zoom */
.pub-fig {
  width: 200px;
  min-width: 200px;
  height: 135px;
  overflow: hidden;
  border-radius: 8px;
  background: var(--white);
  box-shadow: 0 3px 12px rgba(0,0,0,0.10);
  flex-shrink: 0;
  cursor: zoom-in;
}
.pub-fig img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  padding: 4px;
  background: #fff;
  transition: transform 0.35s ease;
}
.pub-fig:hover img { transform: scale(1.10); }

/* Publication text */
.pub-desc { flex: 1; min-width: 0; }

.pub-title {
  font-size: 15.5px;
  font-weight: 600;
  line-height: 1.45;
  margin-bottom: 6px;
}
.pub-title a {
  color: var(--ink);
  text-decoration: none;
  background-image: linear-gradient(currentColor, currentColor);
  background-size: 0 1.5px;
  background-repeat: no-repeat;
  background-position: 0 100%;
  transition: background-size 0.25s ease, color 0.2s ease;
  padding-bottom: 1px;
}
.pub-title a::after {
  content: "↗";
  font-size: 0.9em;
  color: var(--ink-light);
  margin-left: 4px;
  transition: color 0.2s, transform 0.2s;
  display: inline-block;
}
.pub-title a:hover {
  color: var(--crimson);
  background-size: 100% 1.5px;
  text-decoration: none;
}
.pub-title a:hover::after {
  color: var(--crimson);
  transform: translate(2px, -2px);
}

.pub-authors {
  font-size: 14px;
  color: var(--ink-soft);
  margin-bottom: 4px;
  line-height: 1.5;
}
.pub-venue {
  font-size: 14px;
  color: var(--ink-soft);
  margin-bottom: 10px;
  font-style: italic;
}

/* Resource buttons */
.pub-resources {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.pub-resources a {
  display: inline-block;
  padding: 4px 13px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
  text-decoration: none;
  border: 1px solid rgba(0,0,0,0.09);
  transition: transform 0.18s ease, box-shadow 0.18s ease, background 0.18s ease, color 0.18s ease;
  box-shadow: 0 2px 4px rgba(0,0,0,0.10), inset 0 1px 0 rgba(255,255,255,0.55);
}
.pub-resources a:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 14px rgba(0,0,0,0.16), inset 0 1px 0 rgba(255,255,255,0.35);
  text-decoration: none;
}

.btn-paper {
  background: linear-gradient(180deg, #fff 0%, #e0e5ea 100%);
  color: #24292e;
  border-color: #c5cad0;
}
.btn-paper:hover {
  background: linear-gradient(180deg, #444d56 0%, #1b1f23 100%);
  color: #fff !important;
}

.btn-arxiv {
  background: linear-gradient(180deg, #fff0ee 0%, #f8d3d0 100%);
  color: #b31b1b;
  border-color: #eaa8a5;
}
.btn-arxiv:hover {
  background: linear-gradient(180deg, #d63634 0%, #a51717 100%);
  color: #fff !important;
}

.btn-code {
  background: linear-gradient(180deg, #b8bfc8 0%, #8a94a3 100%);
  color: #fff;
  border-color: #6b7280;
}
.btn-code:hover {
  background: linear-gradient(180deg, #6b7280 0%, #374151 100%);
  color: #fff !important;
}

.btn-page {
  background: linear-gradient(180deg, #e8f4ff 0%, #c9e0f8 100%);
  color: #1a5fa8;
  border-color: #a0c4e8;
}
.btn-page:hover {
  background: linear-gradient(180deg, #2563eb 0%, #1d4ed8 100%);
  color: #fff !important;
}

.btn-project {
  background: linear-gradient(180deg, #edfaf3 0%, #c6eedd 100%);
  color: #166534;
  border-color: #86efac;
}
.btn-project:hover {
  background: linear-gradient(180deg, #16a34a 0%, #15803d 100%);
  color: #fff !important;
}

.btn-benchmark {
  background: linear-gradient(180deg, #f3f0ff 0%, #ddd6fe 100%);
  color: #5b21b6;
  border-color: #c4b5fd;
}
.btn-benchmark:hover {
  background: linear-gradient(180deg, #7c3aed 0%, #6d28d9 100%);
  color: #fff !important;
}

.btn-poster {
  background: linear-gradient(180deg, #fff7ed 0%, #fed7aa 100%);
  color: #9a3412;
  border-color: #fdba74;
}
.btn-poster:hover {
  background: linear-gradient(180deg, #ea580c 0%, #c2410c 100%);
  color: #fff !important;
}


/* ── SERVICES ────────────────────────────────────── */
.service-list {
  list-style: none;
  padding: 0;
  margin-bottom: 4px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.service-list li {
  font-size: 14.5px;
  color: var(--ink-soft);
  padding-left: 16px;
  position: relative;
}
.service-list li::before {
  content: '—';
  position: absolute;
  left: 0;
  color: var(--crimson);
  font-weight: 600;
}
.service-list a {
  color: var(--ink-soft);
  transition: color 0.18s;
}
.service-list a:hover { color: var(--crimson); text-decoration: none; }


/* ── FOOTER ──────────────────────────────────────── */
footer {
  background: var(--crimson-pale);
  border-top: 1px solid var(--border);
  padding: 32px 0;
  text-align: center;
}
.footer-text {
  font-size: 14px;
  color: var(--ink-soft);
}
.footer-text a { color: var(--crimson); }
.footer-copy {
  font-size: 12px;
  color: var(--ink-light);
  margin-top: 4px;
}


/* ── ANIMATIONS ──────────────────────────────────── */
.fade-in {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}
.fade-in.visible { opacity: 1; transform: translateY(0); }
.delay-1 { transition-delay: 0.12s; }
.delay-2 { transition-delay: 0.24s; }


/* ── RESPONSIVE ──────────────────────────────────── */
@media (max-width: 860px) {
  .bio-grid {
    grid-template-columns: 1fr;
    gap: 36px;
  }
  .bio-left {
    flex-direction: row;
    align-items: flex-start;
    text-align: left;
    gap: 24px;
  }
  .identity { text-align: left; }
  .social-links { justify-content: flex-start; }
}

@media (max-width: 640px) {
  .bio-left { flex-direction: column; align-items: center; }
  .identity { text-align: center; }
  .social-links { justify-content: center; }
  .contact-edu-grid { grid-template-columns: 1fr; gap: 20px; }
  .ul-papers > li { flex-direction: column; }
  .pub-fig { width: 100%; height: 200px; min-width: unset; }
  #nav-menu { display: none; flex-direction: column; gap: 0; position: fixed; top: var(--nav-h); left: 0; right: 0; background: rgba(255,255,255,0.97); padding: 12px 0; border-bottom: 1px solid var(--border); box-shadow: 0 8px 24px rgba(0,0,0,.08); }
  #nav-menu.open { display: flex; }
  #nav-menu li a { display: block; padding: 12px 24px; }
  .nav-toggle { display: block; }
  .projects-grid { grid-template-columns: 1fr; }
}