Board Thread:Support Requests - Designing Your Wiki/@comment-31305254-20180802214947/@comment-1038387-20180803142119

Keep in mind, all solutions people will give you are for PERSONAL use only. Using this across your wiki is a violation of the Customization policy. A popular solution by people who don't like the current skin is PseudoMonobook.

I would generally advise against making heavy changes to your personal viewing experience, because it makes you completely blind at what other people see it.

Some counter points just for the heck of it:
 * People like to call it "wasting space", but very few websites (that pay people for web design) today actually cover the entire width of the screen. Research shows it's easier to retain the reader's attention if they don't need to move their head to finish the sentence. A fully filled screen only distracts.
 * I don't see "enormous blank space" in the internal content column. Do you mean the pretty normal margins?
 * If you widen the window, you just do it on your monitor. It doesn't alter what's on the monitor.
 * There's the global nav with the search bar, and then the WikiNav which allows admins to link some popular and/or important pages. They take up some space, but the global nav takes up less space than the browser's top section. The WikiNav scrolls away. If you think this takes up vertical space, wait til your wiki gets videos...