Custom Themes (With CSS?)

After Using Discord for a while I can tell that a lot of it seems to be based much like a webpage, and of course you can open it in browser as well. I had an interesting thought of Custom themes. Where you can edit certain properties of elements with CSS to make them look nicer. Maybe even a theme uploader/browser where people can submit their themes. If not CSS Maybe a JSON containing values? I think that this would make a nice addition to people who just discord frequently and just want to change it up