/* =====================
   Hwijae Son – Academic Homepage
   ===================== */

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --navy: #1a2e4a;
  --accent: #2563eb;
  --accent-light: #dbeafe;
  --text: #1f2937;
  --muted: #6b7280;
  --border: #e5e7eb;
  --bg: #ffffff;
  --bg-alt: #f9fafb;
  --max-w: 860px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  color: var(--text);
  background: var(--bg);
}

/* ── Navigation ── */
nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--navy);
  box-shadow: 0 1px 4px rgba(0,0,0,.25);
}

nav .nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  gap: 8px;
  height: 56px;
}

nav .nav-brand {
  color: #fff;
  font-weight: 700;
  font-size: 1.05rem;
  text-decoration: none;
  margin-right: auto;
  white-space: nowrap;
}

nav a {
  color: rgba(255,255,255,.82);
  text-decoration: none;
  font-size: 0.9rem;
  padding: 6px 12px;
  border-radius: 6px;
  transition: background .15s, color .15s;
}

nav a:hover,
nav a.active {
  background: rgba(255,255,255,.15);
  color: #fff;
}

/* ── Main Layout ── */
main {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 48px 24px 80px;
}

/* ── Page Header ── */
.page-header {
  margin-bottom: 40px;
  padding-bottom: 20px;
  border-bottom: 2px solid var(--accent);
}

.page-header h1 {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--navy);
}

/* ── Home Profile ── */
.profile {
  display: flex;
  gap: 32px;
  align-items: flex-start;
  margin-bottom: 40px;
}

.profile-avatar {
  width: 160px;
  height: auto;
  border-radius: 8px;
  object-fit: cover;
  border: 1px solid var(--border);
  flex-shrink: 0;
}

.profile-avatar-placeholder {
  width: 130px;
  height: 130px;
  border-radius: 50%;
  background: var(--accent-light);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--accent);
  flex-shrink: 0;
}

.profile-info h1 {
  font-size: 2rem;
  font-weight: 800;
  color: var(--navy);
  margin-bottom: 4px;
}

.profile-info .title {
  color: var(--muted);
  font-size: 0.95rem;
  margin-bottom: 12px;
}

.profile-info p {
  font-size: 0.95rem;
  line-height: 1.65;
  margin-bottom: 10px;
}

/* ── Contact Box ── */
.contact-box {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 20px 24px;
  margin-top: 32px;
}

.contact-box h2 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: 12px;
}

.contact-box table {
  border-collapse: collapse;
  width: 100%;
}

.contact-box td {
  padding: 4px 0;
  font-size: 0.92rem;
  vertical-align: top;
}

.contact-box td:first-child {
  font-weight: 600;
  color: var(--muted);
  width: 90px;
  padding-right: 16px;
}

/* ── Section headings ── */
.section {
  margin-top: 48px;
}

.section h2 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: 20px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

/* ── Publications ── */
.pub-list {
  list-style: none;
}

.pub-list li {
  padding: 14px 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.93rem;
  line-height: 1.6;
}

.pub-list li:last-child { border-bottom: none; }

.pub-num {
  font-weight: 700;
  color: var(--accent);
  margin-right: 6px;
}

.pub-badge {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 99px;
  margin-left: 6px;
  vertical-align: middle;
}

.badge-review {
  background: #fef3c7;
  color: #92400e;
}

.badge-conf {
  background: #dbeafe;
  color: #1e40af;
}

.badge-award {
  background: #d1fae5;
  color: #065f46;
}

.pub-venue {
  color: var(--muted);
  font-style: italic;
}

/* ── Talks ── */
.talk-list {
  list-style: none;
}

.talk-item {
  display: grid;
  grid-template-columns: 110px 1fr;
  gap: 12px;
  padding: 12px 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.93rem;
}

.talk-item:last-child { border-bottom: none; }

.talk-date {
  color: var(--muted);
  font-size: 0.85rem;
  padding-top: 2px;
}

.talk-title { font-weight: 600; color: var(--navy); }
.talk-venue { color: var(--muted); font-size: 0.88rem; }

/* ── Projects ── */
.project-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-bottom: 32px;
}

.project-card {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 18px 20px;
}

.project-card .year {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: .05em;
  margin-bottom: 6px;
}

.project-card p {
  font-size: 0.92rem;
  line-height: 1.5;
  color: var(--text);
}

.grant-list {
  list-style: none;
}

.grant-list li {
  padding: 12px 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.93rem;
}

.grant-list li:last-child { border-bottom: none; }

/* ── Students ── */
.student-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-bottom: 32px;
}

.student-card {
  text-align: center;
  padding: 20px 16px;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
}

.student-avatar {
  width: 70px;
  height: 70px;
  border-radius: 50%;
  background: var(--accent-light);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--accent);
  margin: 0 auto 12px;
}

.student-name {
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--navy);
  margin-bottom: 6px;
}

.student-avatar-photo {
  width: 140px;
  height: 140px;
  border-radius: 50%;
  object-fit: cover;
  margin: 0 auto 12px;
  display: block;
  border: 2px solid var(--border);
}

.student-notes {
  font-size: 0.82rem;
  color: var(--muted);
  line-height: 1.5;
}

.former-list {
  list-style: none;
}

.former-list li {
  padding: 10px 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.92rem;
}

.former-list li:last-child { border-bottom: none; }

/* ── Links ── */
a {
  color: var(--accent);
  text-decoration: none;
}

a:hover { text-decoration: underline; }

/* ── Footer ── */
footer {
  text-align: center;
  padding: 24px;
  font-size: 0.82rem;
  color: var(--muted);
  border-top: 1px solid var(--border);
}

/* ── Filter Bar ── */
.filter-bar {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 18px;
  margin-bottom: 28px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.filter-group {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.filter-label {
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: .06em;
  width: 52px;
  flex-shrink: 0;
}

.filter-btn {
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 500;
  padding: 4px 12px;
  border-radius: 99px;
  cursor: pointer;
  transition: background .15s, color .15s, border-color .15s;
  font-family: inherit;
}

.filter-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.filter-btn.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

/* ── Pub count badge ── */
.year-count {
  font-size: 0.78rem;
  font-weight: 500;
  color: var(--muted);
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 99px;
  padding: 1px 9px;
  margin-left: 8px;
}

/* ── Accordion Year Groups ── */
.year-group {
  margin-bottom: 4px;
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
}

.year-toggle {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 18px;
  background: var(--bg-alt);
  border: none;
  cursor: pointer;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 700;
  color: var(--navy);
  text-align: left;
  transition: background .15s;
}

.year-toggle:hover { background: #eef2f9; }

.toggle-icon {
  font-size: 1.1rem;
  color: var(--muted);
  transition: transform .2s;
  flex-shrink: 0;
}

.year-group.open .toggle-icon { transform: rotate(180deg); }

.year-body {
  display: none;
  padding: 4px 0 8px;
}

.year-group.open .year-body { display: block; }

/* ── Pub item (inside accordion) ── */
.pub-item {
  display: flex;
  gap: 12px;
  padding: 12px 18px;
  border-bottom: 1px solid var(--border);
  font-size: 0.92rem;
  line-height: 1.6;
  align-items: flex-start;
}

.pub-item:last-child { border-bottom: none; }

.pub-item.hidden { display: none; }

.pub-item-num {
  font-weight: 700;
  color: var(--accent);
  flex-shrink: 0;
  min-width: 30px;
}

.pub-item-body { flex: 1; }

.pub-item-title { margin-bottom: 4px; }

.pub-item-meta {
  color: var(--muted);
  font-size: 0.85rem;
  font-style: italic;
  margin-bottom: 6px;
}

.pub-tags { display: flex; gap: 6px; flex-wrap: wrap; }

.tag {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 99px;
  letter-spacing: .02em;
}

.tag-journal    { background: #dbeafe; color: #1e40af; }
.tag-conference { background: #ede9fe; color: #5b21b6; }
.tag-preprint   { background: #fef3c7; color: #92400e; }
.tag-piml       { background: #d1fae5; color: #065f46; }
.tag-ds         { background: #fce7f3; color: #9d174d; }
.tag-kw         { background: #f1f5f9; color: #334155; }
.tag-kw-teal    { background: #ccfbf1; color: #0f766e; }
.tag-kw-amber   { background: #fef3c7; color: #92400e; }
.tag-kw-indigo  { background: #e0e7ff; color: #3730a3; }
.tag-kw-violet  { background: #ede9fe; color: #6d28d9; }
.tag-kw-rose    { background: #ffe4e6; color: #9f1239; }
.tag-kw-sky     { background: #e0f2fe; color: #0369a1; }
.tag-kw-lime    { background: #ecfccb; color: #3f6212; }

.tag-award { background: #fef9c3; color: #713f12; }

/* ── Empty state ── */
.no-results {
  text-align: center;
  padding: 32px;
  color: var(--muted);
  font-size: 0.92rem;
  display: none;
}

/* ── Responsive ── */
@media (max-width: 640px) {
  html, body { overflow-x: hidden; }

  /* Nav: single scrollable row */
  nav .nav-inner {
    flex-wrap: nowrap;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
    height: 48px;
    padding: 0 12px;
    gap: 2px;
  }
  nav .nav-inner::-webkit-scrollbar { display: none; }
  nav .nav-brand { flex-shrink: 0; font-size: 0.88rem; margin-right: 4px; }
  nav a { flex-shrink: 0; padding: 4px 8px; font-size: 0.75rem; white-space: nowrap; }

  main { padding: 32px 16px 60px; }

  .profile { flex-direction: column; align-items: center; text-align: center; }
  .profile-avatar { width: 130px; }

  .project-grid { grid-template-columns: 1fr; }
  .student-grid { grid-template-columns: 1fr; }
  .talk-item { grid-template-columns: 1fr; gap: 4px; }
}