This is shockingly common but do these people resize their window for every site they visit? Or they keep the window narrow and then sites with side navigation need to put it somewhere else?
Having a large window should be telling the site "you have this space, make the best of it". Maybe it would be nice to have a built-in CSS property for "desired reading text width" but I think most people can pick a number and it is generally good for most readers.
I'm one of those non-fullscreen browser (and most things in general, other than vim) window people.
> Having a large window should be telling the site "you have this space, make the best of it"
I 100% agree but I interpret this in reverse: if I made my browser window gigantic I expect you to use it. If I make my browser window small I expect you to responsively shrink.
The reason this doesn't happen is that it's pretty hard to build layouts that work across all these different screen sizes. That's generally why you get mobile/tablet/1600x900 desktop layouts and that's it.
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I suspect this is another consequence of the app vs. text tension on the web. Apps are great to fullscreen: you want Spotify or Figma to take up the whole window. You don't want a single sentence to unfurl entirely horizontally. But there's no way to say, "I'm the kind of user who sets the browser window size to as much as you can use, so use it all" or "I'm the kind of user who wants you to center your text elements and take up at most 1600px of space even when my browser window is using 3800px."
> This is shockingly common but do these people resize their window for every site they visit?
I don't. I never use my browser full-screen, but I do size it in whatever way makes it work with whatever else I have going on on my desktop. Usually, this is a very small window.
If that makes a site unusable, and if the site isn't essential, then I just move on to a different site. I'm not going to rearrange things just to accommodate the whims of some random web designer.
I don't resize for every window, but I'm also not bothered about having to resize it if and when it makes sense. It takes longer type in a domain name, so it's hardly a big deal.