markdown.css

:root {
  --color-canvas-default: #00000000;
}

.markdown-body {
  background-color: var(--color-canvas-default);
}

@media (prefers-color-scheme: dark) {
  .markdown-body {
    --color-canvas-default: #00000000;
  }
}

@media (prefers-color-scheme: light) {
  .markdown-body {
    --color-canvas-default: #ffffff00;
  }
}