:root {
  --border: #d0d4da;
  --accent: #7a4bd6;
  --error-bg: rgba(230, 60, 60, 0.22);
  --error-fg: #b3261e;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  color-scheme: light;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: system-ui, sans-serif;
  display: flex;
  flex-direction: column;
  height: 100vh;
}

header {
  padding: 0.6rem 1rem;
  border-bottom: 1px solid var(--border);
}

header h1 {
  margin: 0;
  font-size: 1.2rem;
  display: inline-block;
  margin-right: 1rem;
}

header p { display: inline; margin: 0; color: #444; }

#status {
  margin: 0;
  padding: 0.4rem 1rem;
  background: #fff6d8;
  border-bottom: 1px solid var(--border);
}

main {
  flex: 1;
  min-height: 0;
  display: grid;
  grid-template-columns: 1fr 1fr;
}

.pane {
  min-width: 0;
  min-height: 0;
  display: flex;
  flex-direction: column;
}

#input-pane { border-right: 1px solid var(--border); }

.pane h2 {
  margin: 0;
  padding: 0.45rem 1rem;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: #666;
  border-bottom: 1px solid var(--border);
}

.pane-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  border-bottom: 1px solid var(--border);
}

.pane-header h2 { border-bottom: none; flex: 1; }

.pane-header label { font-size: 0.8rem; color: #666; }

.pane-header select {
  margin-right: 1rem;
  font: inherit;
  font-size: 0.85rem;
  padding: 0.15rem 0.3rem;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: #fff;
}

/* --- Editor with an error-highlight layer behind the textarea --- */

#editor {
  position: relative;
  flex: 1;
  min-height: 8rem;
}

#editor pre,
#editor textarea {
  /* Both layers must have identical text metrics and box so the
     highlight lines up with the typed text. */
  margin: 0;
  border: 0;
  padding: 0.6rem 0.8rem;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.45;
  white-space: pre;
  overflow-wrap: normal;
  tab-size: 4;
}

#highlight-layer,
#syntax-layer {
  position: absolute;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
}

/* Error layer: invisible text, only range backgrounds. */
#highlight-layer { color: transparent; }

#highlight-layer mark {
  color: transparent;
  background: var(--error-bg);
  border-radius: 2px;
}

/* Syntax layer: the visible text (hljs token colors on top). */
#syntax-layer { color: #222; background: transparent; }

#source {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  resize: none;
  background: transparent;
  /* Text is drawn by the syntax layer; keep the caret and selection. */
  color: transparent;
  caret-color: #222;
  outline: none;
}

#source::selection { background: rgba(122, 75, 214, 0.25); }

#source:focus-visible { box-shadow: inset 0 0 0 2px var(--accent); }

/* --- Error list --- */

#errors {
  margin: 0;
  padding: 0.4rem 0;
  list-style: none;
  max-height: 30%;
  overflow: auto;
  border-top: 1px solid var(--border);
  background: #fff5f5;
}

#errors li {
  padding: 0.15rem 1rem;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--error-fg);
  cursor: pointer;
}

#errors li:hover { text-decoration: underline; }

#errors li .pos { font-weight: 600; }

/* --- Output tabs --- */

.tabs {
  display: flex;
  gap: 0.25rem;
  padding: 0.3rem 0.6rem 0;
  border-bottom: 1px solid var(--border);
}

.tabs button {
  border: 1px solid var(--border);
  border-bottom: none;
  border-radius: 6px 6px 0 0;
  background: #f2f3f5;
  padding: 0.35rem 0.8rem;
  font: inherit;
  font-size: 0.85rem;
  cursor: pointer;
}

.tabs button[aria-selected="true"] {
  background: #fff;
  font-weight: 600;
  color: var(--accent);
  position: relative;
  top: 1px;
}

.view {
  flex: 1;
  min-height: 0;
  overflow: auto;
  padding: 0.6rem 0.8rem;
}

.view .placeholder { color: #888; font-size: 0.9rem; }

.view svg { max-width: none; }

#expanded {
  margin: 0;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.45;
}

.render-error {
  color: var(--error-fg);
  font-family: var(--mono);
  font-size: 12px;
  white-space: pre-wrap;
}

/* --- Stacked layout (narrow screens) --- */
/* Kept last: these override same-specificity base rules above, which
   would otherwise win by source order. */

@media (max-width: 900px) {
  /* Stacked panes size independently: the output grows with its
     content, the input grows with the typed code. */
  main { grid-template-columns: 1fr; grid-auto-rows: auto; }
  body { height: auto; }
  /* --editor-content-height is measured off the syntax layer in JS.
     flex: none, or the base rule's flex-basis: 0 would override the
     height and pin the editor to its min-height. */
  #editor {
    flex: none;
    height: max(8rem, var(--editor-content-height, 40vh));
  }
  #input-pane { border-right: none; border-bottom: 1px solid var(--border); }
}