Board Thread:Support Requests - Designing Your Wikia/@comment-25343201-20160127191942/@comment-25343201-20161103095028

Stash42 wrote: Ah sorry, I wasn't clear. This is a client side fix, you will need to install the “ Stylish”  extension, then visit that URL and hit “ Install”.

https://addons.mozilla.org/en-gb/firefox/addon/stylish/

https://chrome.google.com/webstore/detail/stylish/fjnbnpbmkenffdnngjfgmeleoegfcffe

You are quite correct that it is a "physical" width issue, hence why my client side fix works! Seriously, if you're running into this on an even semi-regular basis, use the above userstyle.