How to change VIM underlines colors

Question

I'm an author of a VIM colorscheme (danger.vim) and I'd like to change some colors that I can barely see.

This is how it looks in Solarized:

This is how it looks in my theme:

As you can see, it's hard to see the underlines at import sys. I'd make them probably lighter blue, and bold.

I use the Syntastic plugin to integrate with Pyflakes and JSLint mainly.

I also use Flux, probably a reason why it's even harder to see.

Answer 1

In your colorscheme file at:

hi Error   guifg=NONE guibg=NONE gui=undercurl ctermfg=white ctermbg=red cterm=NONE guisp=#FF6C60 " undercurl color

Change the part after guisp to the color you want.

i.e.

hi Error   guifg=NONE guibg=NONE gui=undercurl ctermfg=white ctermbg=red cterm=NONE guisp=#FFFFFF " undercurl color

will make the underlines white

edit: You can make errors bold by change gui=undercurl to gui=bold,undercurl

Answer 2

Seems like Syntastic shows warnings as spell errors, so all I had to do was to define:

SpellBad    word not recognized         |hl-SpellBad|
SpellCap    word not capitalised            |hl-SpellCap|
SpellRare   rare word               |hl-SpellRare|
SpellLocal  wrong spelling for selected region  |hl-SpellLocal|

In my colorscheme file.