Override color for selected variant only

[JoseConseco]

Hi, I just noticed that when I use color override - eg colors = {bg = "#f5f5f5"}, Then all github-nivm themes will use this white color (obviously I do not want to use white for dark themes). It would be great if we coul override color only for selected theme. Something like

colors = {
   github_light = { bg=  white, comment=xyz },
   github_dark = { ... }
}