Stanley Lim’s free UserStyle to UserScript Converter as a Windows .EXE file. Version 1.5, 2017. Download, unzip, drill down to ..\CSStoUserScriptConverter-1.5\CSStoUserScript\bin\.. and run.

My test-convert of a two column layout I cooked up a while back. Works fine. Although the column-splitting method used may be Opera / Chrome specific, as well as the conversion.

eTools is especially useful now that DuckDuckGo searches turn into irrelevant mush 60% of the time.