I have searched for an answer but couldn't find it anywhere. My question is reasonably simple: I have a background color of my body, then a large margin, and now I want a different background color inside the margin.
How do I do that with CSS?
If your margin is set on the body, then setting the background color of the html tag should color the margin area
html { background-color: black; }
body { margin:50px; background-color: white; }
Or as dmackerman suggestions, set a margin of 0, but a border of the size you want the margin to be and set the border-color