Problems with ePub and Kindle

I have published about 35 eBooks on Kindle. I've followed their online directions; I've used Apple's "ePub Best Practices for Pages." Everything looks fine on the "Preview" function while publishing in Kindle; everything looks fine on Amazon after publishing.

It was only after I had published all those books, and months after the fact, that Kindle contacted me:

"1. One or more links in your Table of Contents do not work. The Table of Contents isn't accessible from the "Go To" menu in your book.

2. Text in your book is unreadable for readers using color devices and reading on a black background. This may have occurred due to forcing the font color to black in your source file. To correct this issue, please remove all forced formatting from your font."

Next they gave me these instructions:

"For the Beginning:

Place the cursor where you want the book to start, click on “Insert > Bookmark.” In the "Bookmark name:" field, type “Start” (without the quotes) and click "Add."

For the Table of Contents:

Place the cursor at the beginning of the first entry in the Table of Contents. Click on “Insert > Bookmark.” In the "Bookmark name:" field, type “TOC” (without the quotes) and click "Add.""

After waiting a week they sent me this:

"Our technical team suggest you remove the font setting of black, and ensure your EPUB's font is "automatic". This will resolve the issue and any font color which has been hard-coded."

I'm really frustrated, partly because they waited until after I had published all of my books to let me know there were problems; and partly because I don't quite understand the problems and am a bit lost on how to fix them. I guess I was mistaken in thinking I could use Apple's "ePub Best Practices for Pages" as a template for all the books, and upload them into Kindle.

The instructions they gave me for the TOC problem seem clear enough: in your experience, is this what I need to do to fix each of the books?

I tried to figure out the second one (black vs. automatic font setting), and was unsuccessful.

Can you help?

Thank you.