DuckDuckGo Multi-columns is now fixed: DuckDuckGo – Multi-Columns v.10 at Userstyles.org. This gives you DuckDuckGo search results as a multicolumn layout, suitable for a widescreen desktop PC user rather than a tablet user.
If you need to tweak the rather garish default colours, either backup your existing tweaked script before updating and then paste your prior snippets of code back in again, or use my colour-tweaking guide to fixing the code. It’s only a five minute job.
Note that, to access script editing, you no longer go to User Scripts in Firefox, but rather to: top menu | Tools | Addons | the Firefox Extensions panel | Stylish | Click on the Stylish “Options” button | DuckDuckGo – Multi-Columns v.10 | Edit | Save.