Is there any way to let the player choose the background color? (Harlowe)

And by that I mean the color applied to the entire background, throughout the entire game. Basically this:

html{
background-color: rgb(xxx, xxx, xxx);
}

Except chosen by the player, either once at the beginning of the game or at any time through a link in the header. It would be the simplest thing in the world if variables worked in the stylesheet, but as far as I can tell, they do not. Unfortunately I am not at all well versed in css, so... is there any workaround for this? I am aware that there is the (background:) macro, but that only colors the space immediately under the attached hook and I want the entire background to be filled in (plus I'd like to avoid having to manually apply a macro to literally every single passage in the game if at all possible, though if it's the only way, I'll do it...)