Plugin idea: Narrow columns on post page

I use WordPress for the online version of a newspaper and I just recently transitioned copy editors to doing their work in WordPress. Their one complaint so far is that it is much easier to catch mistakes when articles are in narrow columns in InDesign or InCopy than the wider screen in WordPress. Asking them to make their window size narrow is one solution, but then they just have one really long column.

Is there a (relatively) simple way with CSS or JS to make the main post textarea into many narrow columns with text flowing from one column to the next? I guess I envision this similar to the experience viewing multiple columns of text in Microsoft Word.

Just to be clear, I’m asking about a modification for the admin area, not for front-end display.