Choosing colors (styles)

All options that have a name like --*-style work in the same way. It is very similar to how colors/styles are specified in a gitconfig file: https://git-scm.com/docs/git-config#Documentation/git-config.txt-color

Here's an example:

[delta]
    minus-style = red bold ul "#ffeeee"

That means: For removed lines, set the foreground (text) color to 'red', make it bold and underlined, and set the background color to #ffeeee.

For full details, see the STYLES section in delta --help.