:root {
  --ui-bg: #0e1116;
  --ui-panel: #161b22;
  --ui-panel-2: #1c232d;
  --ui-line: #2a323d;
  --ui-fg: #e6edf3;
  --ui-dim: #8b949e;
  --ui-accent: #4c8dff;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html, body { height: 100%; }

body {
  margin: 0;
  background: var(--ui-bg);
  color: var(--ui-fg);
  font: 14px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  display: flex;
  flex-direction: column;
}

/* ---------- top bar ---------- */

.topbar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 16px;
  background: var(--ui-panel);
  border-bottom: 1px solid var(--ui-line);
  flex: 0 0 auto;
}

.topbar h1 {
  margin: 0;
  font-size: 17px;
  font-weight: 650;
  letter-spacing: -0.01em;
}

.tagline { color: var(--ui-dim); font-size: 13px; }

.spacer { flex: 1; }

button {
  font: inherit;
  font-size: 13px;
  color: var(--ui-fg);
  background: var(--ui-panel-2);
  border: 1px solid var(--ui-line);
  border-radius: 7px;
  padding: 7px 13px;
  cursor: pointer;
}

button:hover { background: #232c38; }

button.primary {
  background: var(--ui-accent);
  border-color: var(--ui-accent);
  color: #fff;
  font-weight: 550;
}

button.primary:hover { background: #3d7cf0; }

/* ---------- layout ---------- */

main {
  flex: 1;
  display: grid;
  grid-template-columns: minmax(380px, 42%) 1fr;
  min-height: 0;
}

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

.pane-input { border-right: 1px solid var(--ui-line); }

.pane-head {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 14px;
  border-bottom: 1px solid var(--ui-line);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ui-dim);
  flex: 0 0 auto;
}

.warn { color: #f0a04b; text-transform: none; letter-spacing: 0; }
.dims { margin-left: auto; text-transform: none; letter-spacing: 0; }

/* ---------- editor ---------- */

#code {
  flex: 1;
  min-height: 180px;
  resize: none;
  border: 0;
  outline: 0;
  padding: 14px;
  background: var(--ui-bg);
  color: var(--ui-fg);
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.55;
  tab-size: 4;
}

/* ---------- controls ---------- */

.controls {
  flex: 0 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 12px 16px;
  padding: 14px;
  border-top: 1px solid var(--ui-line);
  background: var(--ui-panel);
  max-height: 46vh;
  overflow-y: auto;
}

.ctl { display: flex; flex-direction: column; gap: 5px; min-width: 0; }
.ctl-wide { grid-column: 1 / -1; }

.ctl > label {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ui-dim);
}

.ctl output { color: var(--ui-fg); font-variant-numeric: tabular-nums; }

select, input[type="text"] {
  font: inherit;
  font-size: 13px;
  color: var(--ui-fg);
  background: var(--ui-panel-2);
  border: 1px solid var(--ui-line);
  border-radius: 6px;
  padding: 6px 8px;
  width: 100%;
}

input[type="range"] { width: 100%; accent-color: var(--ui-accent); }

.ctl-checks {
  grid-column: 1 / -1;
  flex-direction: row;
  flex-wrap: wrap;
  gap: 8px 18px;
}

.ctl-checks label {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--ui-fg);
  text-transform: none;
  letter-spacing: 0;
  cursor: pointer;
}

input[type="checkbox"] { accent-color: var(--ui-accent); }

/* ---------- preview stage ---------- */

.stage {
  flex: 1;
  min-height: 0;
  overflow: auto;
  padding: 24px;
  display: grid;
  place-items: center;
  /* checkerboard so transparent backgrounds are legible */
  background-color: #0a0d12;
  background-image:
    linear-gradient(45deg, #12161d 25%, transparent 25%),
    linear-gradient(-45deg, #12161d 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, #12161d 75%),
    linear-gradient(-45deg, transparent 75%, #12161d 75%);
  background-size: 20px 20px;
  background-position: 0 0, 0 10px, 10px -10px, -10px 0;
}

.stage svg {
  max-width: 100%;
  height: auto;
  border-radius: 4px;
}

/* ---------- present mode ---------- */

/* Presenting is driven by this class, NOT by :fullscreen — the native API is
 * only a bonus layered on top to hide the browser chrome. That way the button
 * always does something visible, even where the Fullscreen API is missing
 * (iPhone) or refuses the request.
 *
 * Note: :fullscreen and :-webkit-full-screen must stay in SEPARATE rules
 * below. A selector list is discarded whole if any selector in it is
 * unrecognized, which silently killed all of this styling in Safari. */

body.presenting .topbar,
body.presenting .pane-input,
body.presenting .pane-preview > .pane-head {
  display: none;
}

body.presenting main { grid-template-columns: 1fr; }

body.presenting .stage {
  position: fixed;
  inset: 0;
  z-index: 9999;
  padding: 3vmin;
  background: #0a0d12;
  background-image: none;
}

body.presenting .stage svg {
  width: 100%;
  height: 100%;
  max-width: none;
  border-radius: 0;
}

/* Hint how to get out, then fade away. */
body.presenting .stage::after {
  content: "Esc to exit";
  position: fixed;
  bottom: 16px;
  right: 20px;
  padding: 5px 11px;
  border-radius: 6px;
  background: rgba(0, 0, 0, 0.55);
  color: #fff;
  font-size: 12px;
  letter-spacing: 0.04em;
  animation: fade-hint 2.6s ease forwards;
  pointer-events: none;
}

@keyframes fade-hint {
  0%, 60% { opacity: 1; }
  100% { opacity: 0; }
}

@media (prefers-reduced-motion: reduce) {
  body.presenting .stage::after { animation: none; opacity: 0.7; }
}

/* When the native API does engage, the stage is the fullscreen element and
 * gets a black backdrop from the UA. Keep our padding on it. Separate rules,
 * one per prefix — see the note above. */
.stage:fullscreen { padding: 3vmin; background: #0a0d12; background-image: none; }
.stage:-webkit-full-screen { padding: 3vmin; background: #0a0d12; background-image: none; }

@media (max-width: 900px) {
  main { grid-template-columns: 1fr; }
  .pane-input { border-right: 0; border-bottom: 1px solid var(--ui-line); }
}