19/03/2014 tested with a number of userscripts. The 'YouTube Sort by date' userscript lists results in columns for several sites and obviously for this style to make sense you might want to change line 183 to

list.style.setProperty("width", "100%", "important");

and delete line 182 for that matter, or delete the whole duckduckgo block, to allow the css to do its work when the page size changes.