/* ---- Theme tokens ---------------------------------------------------- */
:root {
  --bg: #ffffff;
  --panel-bg: #f7f7f8;
  --fg: #1a1a1c;
  --fg-muted: #55555c;
  --border: #d8d8de;
  --link-stroke: #b6b6bf;
  --node-stroke: #ffffff;
  --label-halo: #ffffff;
  --accent-bg: #ececf1;
  --focus: #1a1a1c;
  --term-link: #4b45a8;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #17171a;
    --panel-bg: #202024;
    --fg: #f0f0f2;
    --fg-muted: #b0b0b8;
    --border: #3a3a42;
    --link-stroke: #5c5c66;
    --node-stroke: #17171a;
    --label-halo: #17171a;
    --accent-bg: #2c2c33;
    --focus: #f0f0f2;
    --term-link: #aaa4f2;
  }
}

* { box-sizing: border-box; }

html, body { margin: 0; padding: 0; }

body {
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.5;
  padding: 1.25rem;
  max-width: 1400px;
  margin: 0 auto;
}

.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* ---- Header ---------------------------------------------------------- */
.page-header { margin-bottom: 1rem; }

.page-header h1 {
  font-size: 1.5rem;
  font-weight: 600;
  margin: 0 0 0.25rem;
  letter-spacing: -0.01em;
}

.subtitle {
  margin: 0 0 0.25rem;
  color: var(--fg-muted);
  font-size: 0.95rem;
}

.subtitle a,
.page-footer a {
  color: var(--term-link);
  text-decoration: underline;
}

.subtitle a:hover,
.page-footer a:hover { text-decoration-thickness: 2px; }

.instruction {
  margin: 0;
  color: var(--fg-muted);
  font-size: 0.875rem;
}

/* ---- Toolbar: legend + controls -------------------------------------- */
.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.5rem;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  margin-bottom: 1rem;
}

.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 0.375rem 1rem;
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: 0.875rem;
}

.legend li { display: flex; align-items: center; gap: 0.4rem; }

.chip {
  width: 0.75rem;
  height: 0.75rem;
  border-radius: 2px;
  flex: none;
  display: inline-block;
}

.controls {
  display: flex;
  gap: 0.5rem;
  align-items: flex-start;
}

.search-wrap { position: relative; }

input[type="search"] {
  font: inherit;
  font-size: 0.875rem;
  padding: 0.4rem 0.6rem;
  width: 14rem;
  max-width: 100%;
  color: var(--fg);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 3px;
  -webkit-appearance: none;
  appearance: none;
}

button {
  font: inherit;
  font-size: 0.875rem;
  padding: 0.4rem 0.7rem;
  color: var(--fg);
  background: var(--accent-bg);
  border: 1px solid var(--border);
  border-radius: 3px;
  cursor: pointer;
}

button:hover { border-color: var(--fg-muted); }

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

.search-results {
  position: absolute;
  z-index: 10;
  top: calc(100% + 2px);
  left: 0;
  width: 14rem;
  max-width: 80vw;
  max-height: 15rem;
  overflow-y: auto;
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 3px;
}

.search-results li { border-bottom: 1px solid var(--border); }
.search-results li:last-child { border-bottom: 0; }

.search-results button {
  display: block;
  width: 100%;
  text-align: left;
  background: none;
  border: 0;
  border-radius: 0;
  padding: 0.4rem 0.6rem;
}

.search-results button:hover,
.search-results button[aria-selected="true"] { background: var(--accent-bg); }

.search-results .no-match {
  padding: 0.4rem 0.6rem;
  color: var(--fg-muted);
  font-size: 0.875rem;
}

/* ---- Layout: graph + detail panel ------------------------------------ */
.layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 21rem;
  gap: 1rem;
  align-items: start;
}

.layout.no-panel { grid-template-columns: minmax(0, 1fr); }

.graph-panel { min-width: 0; }

#graph {
  border: 1px solid var(--border);
  border-radius: 3px;
  background: var(--panel-bg);
  height: 65vh;
  min-height: 420px;
  overflow: hidden;
  touch-action: none;
}

#graph svg { display: block; width: 100%; height: 100%; }

.status {
  margin: 0.4rem 0 0;
  font-size: 0.8125rem;
  color: var(--fg-muted);
  min-height: 1.2em;
}

/* ---- Graph elements -------------------------------------------------- */
.link {
  stroke: var(--link-stroke);
  stroke-width: 1;
  fill: none;
}

.node { cursor: pointer; }
.node circle { stroke: var(--node-stroke); stroke-width: 1.5px; }

.node text {
  font-size: 11px;
  fill: var(--fg);
  stroke: var(--label-halo);
  stroke-width: 3px;
  paint-order: stroke;
  stroke-linejoin: round;
  user-select: none;
  /* The label is part of the node's hit area: clicking a term's name should
     select it, not fall through to the background and clear the selection.
     "all" covers the gaps between glyphs too, so the whole label responds
     rather than only the painted strokes. */
  pointer-events: all;
  cursor: pointer;
}

.node, .link { transition: opacity 0.15s ease; }

.dimmed { opacity: 0.12; }

.node.selected circle { stroke: var(--fg); stroke-width: 2.5px; }
.node.selected text { font-weight: 700; }
.node.neighbour text { font-weight: 600; }
.link.active { stroke: var(--fg-muted); stroke-width: 2; }

.node:focus { outline: none; }
.node:focus-visible circle { stroke: var(--focus); stroke-width: 3px; }

/* ---- Detail panel ---------------------------------------------------- */
.detail-panel {
  position: relative;
  background: var(--panel-bg);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 1rem 1rem 1.25rem;
  min-width: 0;
}

.detail-panel h2 {
  font-size: 1.125rem;
  font-weight: 600;
  margin: 0 1.75rem 0.375rem 0;
}

.group-line {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  margin: 0 0 0.75rem;
  font-size: 0.8125rem;
  color: var(--fg-muted);
}

.definition { margin: 0 0 1rem; font-size: 0.9375rem; }

.detail-panel h3 {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--fg-muted);
  margin: 0 0 0.5rem;
}

.connected {
  display: flex;
  flex-wrap: wrap;
  gap: 0.375rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.connected button { font-size: 0.8125rem; padding: 0.25rem 0.5rem; }

.close-panel {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  background: none;
  border: 0;
  font-size: 1.25rem;
  line-height: 1;
  padding: 0.2rem 0.4rem;
  color: var(--fg-muted);
}

.close-panel:hover { color: var(--fg); }

.term-link {
  display: inline;
  color: var(--term-link);
  background: none;
  border: 0;
  border-bottom: 1px solid currentColor;
  border-radius: 0;
  padding: 0;
  font: inherit;
  cursor: pointer;
}

.term-link:hover { border-bottom-width: 2px; }

/* ---- Alphabetical list ----------------------------------------------- */
.all-terms { margin-top: 1.5rem; }

.all-terms details {
  border-top: 1px solid var(--border);
  padding-top: 0.75rem;
}

.all-terms summary {
  cursor: pointer;
  font-size: 0.9375rem;
  font-weight: 600;
}

.all-terms dl { margin: 1rem 0 0; }

.all-terms dt {
  font-weight: 600;
  margin-top: 1rem;
  display: flex;
  align-items: baseline;
  gap: 0.4rem;
}

.all-terms dd {
  margin: 0.25rem 0 0;
  color: var(--fg);
  font-size: 0.9375rem;
  max-width: 68ch;
}

.all-terms .group-name {
  font-weight: 400;
  font-size: 0.75rem;
  color: var(--fg-muted);
}

/* ---- Footer ---------------------------------------------------------- */
.page-footer {
  margin-top: 1.5rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border);
  font-size: 0.8125rem;
  color: var(--fg-muted);
}

.page-footer p { margin: 0; }

/* ---- Narrow screens -------------------------------------------------- */
@media (max-width: 760px) {
  body { padding: 0.875rem; }
  .layout, .layout.no-panel { grid-template-columns: minmax(0, 1fr); }
  .toolbar { justify-content: flex-start; }
  .controls { width: 100%; }
  .search-wrap { flex: 1; }
  input[type="search"], .search-results { width: 100%; }
  #graph { height: 55vh; min-height: 340px; }
  .page-header h1 { font-size: 1.25rem; }
}