Sign column color should be improved

This is a top notch theme (thanks for your work) and I realize this "issue" is more of a subjective thing, but the sign column background color could be improved. It's too pronounced and demands too much attention (especially with a lot of splits). Personally I would suggest to make it more aligned (perhaps slightly different shade) with the background.

[lithammer]

This is what I did meanwhile:

augroup colorscheme_customize
  autocmd!
  autocmd ColorScheme two-firewatch highlight! link SignColumn LineNr
augroup END