Today I updated PermianExtinction's Fanfic on my site to have my own custom formatting for the HTML, EPUBs, and PDFs.
Did you know that Calibre can convert a LibreOffice odt file to an epub? Here's an example of what that might look like:
The Empire Needs Children by PermianExtinction
I really like the autogenerated cover pages that calibre makes for epubs. They're simple but stylish. Calibre seems to randomly choose the overall color--I wonder if there's a way to purposely select a particular option. I'm planning to go back and switch my own fic to use calibre instead of LibreOffice to generate the epubs because I really like the covers and because this way I can include an autogenerated Table of Contents from the odt into my epub.