@Ken_Moorhead I have to say that your testing is not working well. You also need to test with various eInk Readers such as Kobo & Kindle. They can perform differently then you think. The programs are not the same.
As for using h1-h4 in the main text, don't. h1-h4 are for headers. Regular text in the main text should be using <p> with or without classes.
As for colors, don't. They don't work well with eInk screens that don't support color.