/* ===========================================================
   Design tokens
   =========================================================== */
:root {
  --color-bg: #0d1117;
  --color-surface: #161b22;
  --color-surface-2: #21262d;
  --color-border: #30363d;
  --color-text: #e6edf3;
  --color-text-muted: #8b949e;
  --color-link: #58a6ff;
  --color-link-hover: #79c0ff;
  --color-accent: #238636;
  --color-accent-hover: #2ea043;
  --color-institution: #58a6ff;
  --color-focus: #58a6ff;
  --color-footer-bg: #010409;
  --color-footer-text: #8b949e;
  --color-footer-text-muted: #6e7681;
  --max-width: 1200px;
  --navbar-height: 64px;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  color-scheme: dark;
}

body {
  background: var(--color-bg);
  color: var(--color-text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.55;
  margin: 0;
  -webkit-font-smoothing: antialiased;
}

.theme-toggle, button[accesskey="t"] { display: none !important; }

a {
  color: var(--color-link);
  text-decoration: none;
}
a:hover { color: var(--color-link-hover); text-decoration: underline; }

h1, h2, h3, h4 {
  color: var(--color-text);
  line-height: 1.2;
  font-weight: 700;
}
h1 { font-size: 1.9rem; margin: 0 0 0.5em; }
h2 { font-size: 1.4rem; margin: 1.6em 0 0.6em; }
h3 { font-size: 1.15rem; margin: 1.3em 0 0.5em; }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ===========================================================
   Accessibility helpers
   =========================================================== */
.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--color-institution);
  color: #fff;
  padding: 0.75em 1.25em;
  z-index: 100;
  border-radius: 0 0 6px 0;
}
.skip-link:focus {
  left: 0;
  outline: 3px solid var(--color-focus);
}

:focus-visible {
  outline: 3px solid var(--color-focus);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

/* ===========================================================
   Navbar
   =========================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
}
.navbar {
  max-width: var(--max-width);
  margin: 0 auto;
  height: var(--navbar-height);
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.navbar-brand {
  font-weight: 800;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  font-size: 1.05rem;
  color: var(--color-text);
}
.navbar-brand:hover { color: var(--color-institution); text-decoration: none; }

.navbar-links {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  list-style: none;
  margin: 0;
  padding: 0;
}
.navbar-links a {
  color: var(--color-text);
  font-size: 0.95rem;
  font-weight: 500;
}
.navbar-links a:hover { color: var(--color-institution); text-decoration: none; border-bottom: 2px solid var(--color-institution); }

.navbar-search-btn {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-text);
  padding: 0.4rem;
  display: flex;
  align-items: center;
}
.navbar-search-btn:hover { color: var(--color-institution); }
.navbar-search-btn svg { width: 20px; height: 20px; }

.navbar-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.4rem;
}
.navbar-toggle svg { width: 26px; height: 26px; }

@media (max-width: 800px) {
  .navbar-links { display: none; }
  .navbar-toggle { display: block; margin-left: auto; }
  .navbar { justify-content: space-between; }
  .navbar-search-btn { order: 2; }
  .navbar-toggle { order: 3; }
  .navbar.is-open .navbar-links {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: var(--navbar-height);
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    padding: 0.5rem 1.5rem 1rem;
    gap: 0;
    align-items: stretch;
  }
  .navbar.is-open .navbar-links a {
    padding: 0.85rem 0;
    border-bottom: 1px solid var(--color-border);
    width: 100%;
  }
}

/* ===========================================================
   Breadcrumbs
   =========================================================== */
.breadcrumbs {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin: 1.25rem 0;
}
.breadcrumbs a { color: var(--color-text-muted); }
.breadcrumbs a:hover { color: var(--color-institution); }
.breadcrumbs .sep { margin: 0 0.4em; }

/* ===========================================================
   Homepage hero
   =========================================================== */
.hero {
  padding: 3rem 0 2rem;
  display: flex;
  gap: 2.5rem;
  align-items: flex-start;
}
.hero-photo {
  flex: 0 0 auto;
}
.hero-photo img {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid var(--color-surface-2);
}
.hero-photo .monogram {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  background: var(--color-institution);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  font-weight: 700;
}
.hero-text { flex: 1 1 auto; }
.hero-text h1 { font-size: 2.1rem; margin-bottom: 0.15em; }
.hero-title { font-size: 1.05rem; color: var(--color-text-muted); margin: 0 0 0.9em; }
.hero-intro { font-size: 1.05rem; margin: 0 0 1.4em; max-width: 62ch; }

.hero-actions { display: flex; gap: 0.75rem; flex-wrap: wrap; }

@media (max-width: 640px) {
  .hero { flex-direction: column; align-items: center; text-align: center; }
  .hero-actions { justify-content: center; }
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.55em 1.1em;
  border-radius: 6px;
  font-size: 0.92rem;
  font-weight: 600;
  cursor: pointer;
  border: 1px solid transparent;
}
.btn-primary {
  background: var(--color-accent);
  color: #fff;
}
.btn-primary:hover { background: var(--color-accent-hover); color: #fff; text-decoration: none; }
.btn-secondary {
  background: transparent;
  border-color: var(--color-border);
  color: var(--color-text);
}
.btn-secondary:hover { border-color: var(--color-institution); color: var(--color-institution); text-decoration: none; }
.btn-chip {
  background: var(--color-surface-2);
  color: var(--color-text);
  font-size: 0.82rem;
  padding: 0.35em 0.8em;
  border-radius: 999px;
}
.btn-chip:hover { background: var(--color-border); text-decoration: none; }

/* ===========================================================
   Research areas (homepage accordions)
   =========================================================== */
.homepage-bio {
  padding: 0.5rem 0 2rem;
}

#selected-works {
  scroll-margin-top: calc(var(--navbar-height) + 12px);
  padding: 1.5rem 0 3rem;
}
.research-area {
  border: 1px solid var(--color-border);
  border-radius: 8px;
  margin-bottom: 0.75rem;
  background: var(--color-surface);
  overflow: hidden;
}
.research-area-toggle {
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  padding: 1rem 1.25rem;
  font-size: 1.05rem;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--color-text);
}
.research-area-toggle .chevron {
  transition: transform 0.18s;
  flex: 0 0 auto;
  margin-left: 1rem;
}
.research-area.is-open .chevron { transform: rotate(180deg); }
.research-area-panel {
  display: none;
  padding: 0 1.25rem 1.25rem;
  border-top: 1px solid var(--color-border);
}
.research-area.is-open .research-area-panel { display: block; }
.research-area-panel .featured-item {
  padding: 0.6rem 0;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.94rem;
}
.research-area-panel .featured-item:last-of-type { border-bottom: none; }
.research-area-view-all { display: inline-block; margin-top: 0.75rem; font-weight: 600; }

@media (prefers-reduced-motion: reduce) {
  .research-area-toggle .chevron { transition: none; }
}

/* ===========================================================
   Dense citation list (Writings page)
   =========================================================== */
.pub-tabs {
  position: sticky;
  top: var(--navbar-height);
  z-index: 20;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  box-shadow: 0 2px 4px rgba(0,0,0,0.35);
  display: flex;
  gap: 0.25rem;
  overflow-x: auto;
  padding: 0.75rem 0;
}
.tab-btn {
  background: none;
  border: none;
  padding: 0.5em 1em;
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--color-text-muted);
  cursor: pointer;
  border-radius: 6px;
  white-space: nowrap;
}
.tab-btn:hover { color: var(--color-text); background: var(--color-surface); }
.tab-btn.active {
  color: var(--color-institution);
  background: var(--color-surface);
  box-shadow: inset 0 -2px 0 var(--color-institution);
}

.writings-layout {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 2rem;
  padding: 1.5rem 0 3rem;
  align-items: start;
}
@media (max-width: 860px) {
  .writings-layout { grid-template-columns: 1fr; }
}

.pub-sidebar {
  position: sticky;
  top: calc(var(--navbar-height) + 60px);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 1.1rem;
  font-size: 0.9rem;
}
@media (max-width: 860px) { .pub-sidebar { position: static; } }

.pub-sidebar h3 {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-muted);
  margin: 1.1rem 0 0.5rem;
}
.pub-sidebar h3:first-child { margin-top: 0; }

.pub-search-input, .pub-select {
  width: 100%;
  padding: 0.5em 0.7em;
  border: 1px solid var(--color-border);
  border-radius: 6px;
  background: var(--color-bg);
  font-size: 0.9rem;
  color: var(--color-text);
}
.pub-select:focus-within, .pub-select:focus { outline: 3px solid var(--color-focus); }

.pub-checkbox-list {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}
.pub-checkbox-list.scrollable {
  max-height: 200px;
  overflow-y: auto;
  padding-right: 0.25rem;
}
.pub-checkbox-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-direction: row;
}
.pub-checkbox-row input[type="checkbox"] {
  flex: 0 0 auto;
  margin: 0;
  width: 16px;
  height: 16px;
}
.pub-checkbox-row label {
  flex: 1 1 auto;
  font-size: 0.88rem;
  cursor: pointer;
}

.pub-reset-btn {
  margin-top: 1.1rem;
  width: 100%;
}

.pub-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1rem;
}
.pub-result-count {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.pub-list {
  list-style: none;
  margin: 0;
  padding: 0;
}
.pub-list-item {
  display: block;
  padding: 0.85rem 0;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.92rem;
  line-height: 1.5;
}
.pub-list-item .pub-authors { color: var(--color-text); }
.pub-list-item .pub-year { color: var(--color-text-muted); }
.pub-list-item .pub-title { font-weight: 600; }
.pub-list-item .pub-title a { color: var(--color-text); }
.pub-list-item .pub-title a:hover { color: var(--color-institution); }
.pub-venue { color: var(--color-text-muted); font-style: italic; }
.pub-list-item .pub-type-badge {
  display: inline-block;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-text-muted);
  background: var(--color-surface-2);
  padding: 0.1em 0.5em;
  border-radius: 4px;
  margin-left: 0.5em;
  vertical-align: middle;
}

/* ===========================================================
   Publication / software single pages
   =========================================================== */
.pub-header { margin: 1.5rem 0 1rem; }
.pub-header .pub-meta { color: var(--color-text-muted); margin: 0.4em 0; }
.pub-header .pub-meta .authors { color: var(--color-text); }
.pub-featured-img {
  width: 100%;
  max-width: 320px;
  border-radius: 8px;
  border: 1px solid var(--color-border);
  float: right;
  margin: 0 0 1rem 1.5rem;
}
@media (max-width: 640px) {
  .pub-featured-img { float: none; margin: 1rem 0; max-width: 100%; }
}
.pub-links { display: flex; gap: 0.6rem; flex-wrap: wrap; margin: 1.2rem 0; }
.pub-abstract { margin: 1.2rem 0; max-width: 72ch; }
.pub-abstract h2 { font-size: 1.05rem; }
.image-credit { font-size: 0.78rem; color: var(--color-text-muted); margin-top: 0.4em; }

.dataset-banner {
  background: var(--color-surface);
  border-left: 3px solid var(--color-accent);
  padding: 0.75em 1em;
  margin: 1rem 0;
  font-size: 0.9rem;
  border-radius: 0 6px 6px 0;
}

/* ===========================================================
   See Also
   =========================================================== */
.gk-see-also {
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--color-border);
}
.gk-see-also ul { list-style: none; margin: 0; padding: 0; }
.gk-see-also li {
  padding: 0.6em 0;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.9rem;
}
.gk-see-also .kind-label {
  display: inline-block;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  color: var(--color-institution);
  font-weight: 700;
  margin-right: 0.5em;
}

/* ===========================================================
   Cards (People page, Software list)
   =========================================================== */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1.25rem;
  margin: 1.5rem 0;
}
.card {
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 1.1rem;
  background: var(--color-surface);
  transition: transform 0.18s, box-shadow 0.18s, border-color 0.18s;
}
.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(0,0,0,0.5);
  border-color: var(--color-institution);
}
@media (prefers-reduced-motion: reduce) {
  .card:hover { transform: none; }
}
.card h3 { margin: 0 0 0.3em; font-size: 1.02rem; }
.card .card-meta { color: var(--color-text-muted); font-size: 0.85rem; }

.people-list { list-style: none; margin: 1.5rem 0; padding: 0; columns: 2; column-gap: 2rem; }
.people-list li { padding: 0.4em 0; break-inside: avoid; }
@media (max-width: 640px) { .people-list { columns: 1; } }

.people-group-title {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-muted);
  margin: 1.6rem 0 0.4rem;
}

/* ===========================================================
   Prose (bio, teaching, contact, single pages)
   =========================================================== */
.prose { max-width: 72ch; }
.prose p { margin: 0 0 1.25em; }
.prose ul, .prose ol { margin: 0 0 1.25em; padding-left: 1.4em; }
@media (max-width: 640px) {
  .prose img[style*="float"] { float: none !important; margin: 0 0 1.25rem !important; max-width: 100% !important; }
}

main { padding-bottom: 2rem; }

/* ===========================================================
   Search modal
   =========================================================== */
.search-modal-backdrop {
  position: fixed; inset: 0;
  background: rgba(1,4,9,0.7);
  z-index: 90;
  display: none;
}
.search-modal-backdrop.is-open { display: block; }
.search-modal {
  position: fixed;
  top: 10vh;
  left: 50%;
  transform: translateX(-50%);
  width: min(600px, 92vw);
  max-height: 70vh;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 10px;
  box-shadow: 0 20px 60px rgba(0,0,0,0.6);
  z-index: 91;
  display: none;
  flex-direction: column;
  overflow: hidden;
}
.search-modal.is-open { display: flex; }
.search-modal-input {
  border: none;
  border-bottom: 1px solid var(--color-border);
  padding: 1rem 1.25rem;
  font-size: 1.05rem;
  background: var(--color-surface);
  color: var(--color-text);
}
.search-modal-input:focus { outline: none; }
.search-modal-results { overflow-y: auto; padding: 0.5rem; }
.search-result-item {
  display: block;
  padding: 0.7em 0.75em;
  border-radius: 6px;
  color: var(--color-text);
}
.search-result-item:hover, .search-result-item.is-selected {
  background: var(--color-surface-2);
  text-decoration: none;
}
.search-result-item .result-type {
  font-size: 0.72rem;
  text-transform: uppercase;
  color: var(--color-text-muted);
}
.search-empty { padding: 1.5rem; color: var(--color-text-muted); text-align: center; }

/* ===========================================================
   Footer
   =========================================================== */
.site-footer {
  background: var(--color-footer-bg);
  color: var(--color-footer-text);
  margin-top: 3rem;
}
.site-footer .container {
  padding: 2rem 1.5rem 1.5rem;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}
.site-footer a { color: var(--color-footer-text); }
.site-footer a:hover { color: #fff; }
.footer-nav { display: flex; gap: 1.25rem; flex-wrap: wrap; list-style: none; margin: 0; padding: 0; }
.footer-credit {
  width: 100%;
  text-align: right;
  font-size: 0.78rem;
  color: var(--color-footer-text-muted);
  padding-top: 1rem;
  border-top: 1px solid rgba(232,224,213,0.15);
  margin-top: 0.5rem;
}
.footer-credit a { color: var(--color-footer-text-muted); text-decoration: underline; }

/* ===========================================================
   404
   =========================================================== */
.error-page { padding: 3rem 0; text-align: center; }