Change color+size of text based on indent level


I’m writing a simple text file of notes for a class and indenting each line of text appropriately to form an outline structure. I think it would be cool and useful if the color of each line of text was different based on its indent level to make the structure of the outline even more clear. If I could also change the font size slightly to make headings (no or low indent lines) larger, that would also be nice.

I presume that these things are possible, but I know very little about writing stylesheets (or whatever else it takes to make them happen). Any ideas or suggestions? Also, should I use a unique file extension to indicate that my file is plain text in outline form, and thus subject to these suggested augmentations?