Hi,
Same here, I tried inspecting the CSS to see if I could make out which CSS elements to modify, but got lost.
This is what the code of the linked post renders (I’m using the default theme in dark mode), with left pane being source, middle is live preview and right is reading mode:
Eventually I would also like to change the ordered lists to use 1, 2, 3… then a, b, c… then i, ii, iii… etc. Both in live preview and reading mode. And I’m guessing that the properties (border and background) used in the code above will not help, but rather something like list-style-type.