:root {
  --bg: #fafafa;
  --node-fill: #ffffff;
  --node-stroke: #555555;
  --text: #1a1a1a;
  --accent: #2f6fde;
  --accent-fill: #e6efff;
  --muted: #555555;
  --warn: #b42318;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #18181b;
    --node-fill: #27272a;
    --node-stroke: #a1a1aa;
    --text: #f4f4f5;
    --accent: #6ea2ff;
    --accent-fill: #1e2a44;
    --muted: #a1a1aa;
    --warn: #ff8a80;
  }
}

html, body {
  margin: 0;
  height: 100%;
  background: var(--bg);
  overflow: hidden;
}

#canvas {
  display: block;
  width: 100vw;
  height: 100vh;
  font-family: system-ui, sans-serif;
  font-size: 16px;
  user-select: none;
}

.node { cursor: pointer; }

#edges line {
  stroke: var(--node-stroke);
  stroke-width: 1.5;
  pointer-events: none;
}

.node ellipse {
  fill: var(--node-fill);
  stroke: var(--node-stroke);
  stroke-width: 1.5;
}

.node text {
  white-space: pre; /* keep repeated spaces, as the text box shows them */
  fill: var(--text);
  text-anchor: middle;
  dominant-baseline: central;
}

.node:hover ellipse { stroke: var(--accent); }

.node.selected ellipse {
  fill: var(--accent-fill);
  stroke: var(--accent);
  stroke-width: 3;
}

/* While editing, the SVG label stays in place (so it can still be measured) but is hidden;
   the HTML input on top shows the text instead. */
.node.editing text { visibility: hidden; }

#toolbar {
  position: fixed;
  top: 12px;
  right: 12px;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 8px;
  font-family: system-ui, sans-serif;
}

#toolbar .buttons {
  display: flex;
  gap: 6px;
}

#toolbar button {
  font: inherit;
  font-size: 14px;
  padding: 6px 12px;
  border: 1px solid var(--node-stroke);
  border-radius: 6px;
  background: var(--node-fill);
  color: var(--text);
  cursor: pointer;
}

#toolbar button:hover:not(:disabled) { border-color: var(--accent); }

#toolbar button:disabled {
  opacity: 0.4;
  cursor: default;
}

#status {
  max-width: 280px;
  font-size: 13px;
  text-align: right;
  color: var(--muted);
}

#status.warn { color: var(--warn); }

#export-panel {
  position: fixed;
  right: 12px;
  bottom: 12px;
  width: min(560px, calc(100vw - 24px));
  height: min(360px, calc(100vh - 120px));
  display: flex;
  flex-direction: column;
  border: 1px solid var(--node-stroke);
  border-radius: 8px;
  background: var(--node-fill);
  color: var(--text);
  font-family: system-ui, sans-serif;
  font-size: 14px;
  box-shadow: 0 4px 20px rgb(0 0 0 / 0.15);
}

#export-panel[hidden] { display: none; }

#export-panel header {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 10px;
  border-bottom: 1px solid var(--node-stroke);
}

#export-panel h2 {
  margin: 0;
  margin-right: auto;
  font-size: 14px;
}

#export-panel label { display: flex; align-items: center; gap: 4px; }

#export-panel button {
  font: inherit;
  padding: 3px 10px;
  border: 1px solid var(--node-stroke);
  border-radius: 6px;
  background: var(--bg);
  color: var(--text);
  cursor: pointer;
}

#export-code {
  flex: 1;
  margin: 0;
  padding: 10px;
  border: none;
  border-radius: 0 0 8px 8px;
  resize: none;
  background: var(--bg);
  color: var(--text);
  font: 13px/1.45 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

#label-editor {
  position: fixed;
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  border: none;
  outline: none;
  background: transparent;
  color: var(--text);
  font-family: system-ui, sans-serif;
  text-align: center;
  resize: none;
  overflow: hidden;
  white-space: pre;
}