Modern YouTube sidebar appears on old layout when using lower resolution screen

[CChap06]

My secondary monitor is an old one: It has an aspect ratio of 4:3 and a resolution of 1024x768. When I load custom tube on it, the modern YouTube sidebar (the one that appears on lower resolution displays) appears. Of course, this isn't really an issue on the more modern layouts; but if I select an older one where this sidebar wouldn't be present, it's kind of a stain on the layout and even obstructs a few elements in some cases.

[lightbeam24]

I know this is going to sound weird, but try enabling "Always show sidebar", and tell me if that fixes things.

[CChap06]

It's pretty strange, but somehow that solved it.

[lightbeam24]

That option forces the regular sidebar to always be visible no matter which page you're on, and no matter your zoom level. I believe it also hides the mini sidebar (the one in your screenshot). It was intended for the modern layouts, but I guess it works on the older layouts too, since the older layouts force hide the sidebar on pages such as the watch page. Perhaps I should bake the functionality into all layouts from 2012 and earlier.