Hogwild What are the (negative) repercussion of the "changing the column size" method?
As @michaelsy said:
michaelsy One disadvantage of a narrower content area is that there may not be enough width for large tables or images.
I would disagree, though, that it's a problem for images as they would adapt to the screen width and can be clicked on to open the original image (depending on syntax used). But it can be a problem for tables. And looking at your wiki it already has that problem even with the bigger width.
I would agree that changing the site width is the best option to restrict the width of the content for everyone. I wouldn't recommend using the Wrap plugin for this purpose as it would be rather tedious to use on every page.
I don't think anyone has described yet how to make those changes. Ask your admin to use the "Template Style Settings" in the admin section. There they can make changes to "The width of the full site". It is set to 75em
by default but your wiki has it set to 108em
. That will be one of the reasons why everything is less readable. Although I suspect that the reason why it was set so high are the wide tables you have on some pages.
Another option no-one has mentioned yet if you are happy with just changing things for yourself and not every reader of your wiki: You can make the browser window smaller! The width of the wiki will automatically adapt to the viewport size.
Another option is to zoom into the page with browser zoom. That has the same effect but will also make everything bigger. As part of either of those two options you might get into the mobile view where the sidebar collapses and some other things change.