diff or vim -d colorscheme

Question

I need a readable colorscheme for vim -d (or vimdiff). My problem is that some lines aren't readable (see picture), white text on yellow background: I tried also the following in ~/.vimrc:

if &diff
   set At_Co=16
   set syntax off
   colorscheme vcbc
endif

I like syntax on and the change of the color didn’t improve. My Questions:

1. How can I get the key word of white text on yellow background so that I can change the colorscheme manually? I tried already ‘highlight’ in vi which shows the keyword and the settings but it didn’t work.
2. An alternative is finding a good colorscheme for vimdiff. I found some who claimed to be optimized for vimdiff like ‘vcbc‘ but it produces the same unreadable text.

I am on Ubuntu 16.04.

Thanks in advance!