Wrapping & overflow issues on GitHub Pages site

[nattheriddle1]

Normally, the side-by-side layout of the GitHub Pages website works wonderfully. But if there is a large amount of content in the output pane, and if this content does not wrap (which is very common, since csso removes whitespace), the editor layout gets completely ruined: the editor pane shrinks, the output pane expands, and the body overflows horizontally.

I can't add a screenshot on GitHub, but the effects are easily reproducible. For example, try pasting in water.css.