you can change the color registers used for displaying the text and its
background, as well as the mode line and its background. You can also select
the way the text (or mode line) is displayed (i.e. plain, bold, italic,
underline, or inverse video). You can do all that using the commands:
set-text-forground, set-text-background, set-text-rendition,
set-mode-forground, set-mode-background, set-mode-rendition. You type these
commands at the M-x prompt (hit Esc X to get that). Experiment with these
commands and you'll see what I mean.
– Steve –