On small viewports, some of the leftmost content can be cut off such that you cannot scroll to the left and view it:

Additionally, a child div is overflowing out of its parent, and as a result there is some area of the page with no background

This is a problem on devices with small viewports (e.g., Chromebooks) where to have a split view (browser on left, editor on right) results in portions of the compiler output not being readable: