WordPress doesn’t currently offer a built‑in way to switch the CodeMirror editor theme, and most older plugins that did this aren’t maintained for 6.9. The cleanest approach is to enqueue a custom stylesheet in your admin area that overrides CodeMirror’s default theme with Monokai (you can grab the CSS from CodeMirror’s official theme files). This way, you avoid editing core files and keep changes update‑safe. If you prefer a plugin route, “WP Editor.md” or “Advanced Code Editor” are more actively maintained concoracard com alternatives that support custom themes and syntax highlighting, though you’ll want to test them carefully on 6.9 before rolling out.
