There are a few different ways of going about this - adjusting only Editing view, only Reading view, and a combination of both with lots of variation in the CSS used.
It really comes down to personal preference and the contents of your notes. Do you just have some headings and paragraphs, or are your notes filled with lists, code blocks, and math equations? The CSS will grow in complexity depending on what elements you want to cover and adjust.
I’d search the forum for some examples to try out. Here are two that you could start with to see how it goes: