what is main editor? show us.
If you mean the code editor (the Monaco code editor) then if the theme does not set by the node-red theme, you can set the monaco theme yourself How to use themes with Monaco editor - #7 by Steve-Mcl
options include "vs", "vs-dark" and anything you see in here: node-red/packages/node_modules/@node-red/editor-client/src/vendor/monaco/dist/theme at master · node-red/node-red · GitHub e.g. "ace", "dawn", "dracula", "birds-of-paradise" etc.