4.11 CSS Cleanup
Making Ebooks with InDesign: Module 4, Step 11
Making Ebooks with InDesign: Module 4, Step 10
InDesign to EPUB
Before reading this, you might want to read:
Add a full set of accessibility metadata. Adding schema.org accessibility metadata to your ebooks is partly aspirational at this point in time but it is slowly getting exposed to consumers in various ways.
The DAISY Knowledge base is a tremendous resource on this topic and, in fact, has a full set of a11y metadata that you can copy into your content, editing as necessary.