Yeah... and doing it on the whole body would be fatiguing on long pages because you have to scroll up and down the whole page after each column. I'd probably want to do column-split content areas over a certain width (e.g. an <article> or something).
I played around with columns a few years ago[0] after I first saw them being used. I use some JS to keep the containing div the same height as the window and hook into scroll events. This was several years ago fairly soon after columns were being implemented and I'm sure there's a better way of doing it today.
Might split out the header separately.