I'm using the
colorscheme monokai and coc.nvim with pylint to lint Python code in Vim (terminal, not GUI, in terminal.app on macOS which I'm pretty sure has 256 colours). The linting pops up on a black background, so errors (red) are basically readable, but hints (blue) are very difficult to read:
Looking at the colorscheme, I wasn't able to figure out which value to change to get a different coloured background for these messages. For instance I would guess that one of these would be relevant:
hi ErrorMsg ctermfg=231 ctermbg=197 cterm=NONE guifg=#f8f8f0 guibg=#f92672 gui=NONE hi WarningMsg ctermfg=231 ctermbg=197 cterm=NONE guifg=#f8f8f0 guibg=#f92672 gui=NONE
But 231 per this website is white, so that doesn't seem to be the right line. Are there some defaults it might be inheriting?
Additional info: this really nifty tip shows a way to echo information about the highlight group under the cursor in normal mode, including name and colour. However it doesn't for the pop-up box that coc uses to show lint messages, so I'm still unsure.