customizing fonts, code font size/syntax coloring, document color, etc.

So I'm able to choose from a range of markdown fonts for the text blocks, but I was wondering if there was any way to customize the code block displays, from the border edges and background color to the syntax highlighting. Not to be too picky, but I noticed the Latex coloring is also slightly grey (and not just black)—is there any way on the user end to customize this?