I tried using this solution and it works, correcting the CSS to the following (the first line was missing an ol {):
.cooked div[data-wrap="letterlist"] ol {
list-style: upper-alpha;
}
However I can’t get it to show in the editor preview window, which is going to be a bit of an issue for most of my users. I’ve tried inspecting with the web browser, and it seems the custom CSS is not loaded or applied to the preview (I’m not a professional at this, so I might be wrong).
Any way you can think of to solve this problem, @Falco?