Generally, I avoid use of colours in my storyfiles, I follow the ancient wisdom, “de gustibus et coloribus non disputandum est”, and I consider that the right of fine-tune the 'terp to their color taste should be added to the player’s bill of rights.
(For the record, sometime ago I have posted a screenshot of my QTads color scheme in another debate…)
I have the header and a map window with a different default background color so they stand out. As for text, the only time I change color is for the in-game help system. I want that to stand apart from the regular game text. And any hyperlinks that appear in the game text are also the color of default hyperlinks from the terp.
My biggest issue is that none of the online interpreters support graphical banner windows with TADS non-web gui, so QTADS is the only real multiplatform solution. It’s a frustrating limitation for anyone attempting to do a bit more for the player experience.
I wanted to use colour to really differentiate text on a computer screen in-game. Having it in its own box with different background and foreground colours can really help sell the difference. And then the interface itself can have bright colours to help draw players towards typing the right things.