The syntax highlighting style I'm using has a light grey font on a white background for the commit message prompt. Where in the syntax highlighting configuration can I tweak the colors used for this?
Settings | Editor | Colors & Fonts | General | Default text
Note that IntelliJ IDEA has custom logic that always uses the background color from the default scheme (ignoring your customizations) in UI elements such as panels and dialog text fields if the UI theme is default (not Darcula) and the editor is configured to use a dark background color. You may want to change the color scheme to Darcula in Settings | Appearance & Behavior | Appearance | Theme.