:root {
  --bg: #0f1419;
  --panel: #1a212b;
  --border: #2b3543;
  --text: #e6edf3;
  --muted: #8b98a5;
  --accent: #4493f8;
  --green: #3fb950;
  --red: #f85149;
  --amber: #d29922;
  --code-bg: #0d1117;
}
/* 4.1 light palette — applied on explicit choice, or by system pref when unset. */
@media (prefers-color-scheme: light) {
  :root:not([data-theme]) {
    --bg: #f5f7fa; --panel: #ffffff; --border: #d7dee6; --text: #1a2028;
    --muted: #5c6773; --accent: #2563eb; --green: #1a7f37; --red: #cf222e;
    --amber: #9a6700; --code-bg: #f0f3f6;
  }
}
:root[data-theme="light"] {
  --bg: #f5f7fa; --panel: #ffffff; --border: #d7dee6; --text: #1a2028;
  --muted: #5c6773; --accent: #2563eb; --green: #1a7f37; --red: #cf222e;
  --amber: #9a6700; --code-bg: #f0f3f6;
}