Fix for deeplearningbook.org (#3700)
Fix for deeplearningbook.org (#3700)

- Invert images inside the book.
- Make the background of the book looks good.
- Resolves #3699
alexanderby/darkreader,darkreader/darkreader,alexanderby/darkreader,darkreader/darkreader,darkreader/darkreader,alexanderby/darkreader