css: make it possible to control console color directly.

css: make it possible to control console color directly.

Having it the same as --code-color makes it impossible to have dark
console listings combined with light code listings. Also while at it,
made .m-inverted line highlighting work with console listings too.

This has a minor visual change for for higlighted .m-inverted lines --
probably by accident those were not reverted back to --code-color, but
rather --color, making them darker than they should be in the dark
theme.