Getting a full-width PR review pane on GitHub temporary private forks

This is the sort of post that will have more preamble than the resulting code, but bear with me. If you're working on security fixes to a project on GitHub, you'll likely be using a temporary private fork to collaborate on. If you do so, as well as things like CI and other GitHub Apps not being enabled on the repo, you'll also find that the PR page doesn't seem to be as responsive as it suggests it will be. For instance: We can see that there's a lot of blank space either side of the PR, which wouldn't be the case on a regular PR: If we use the following client-side Javascript: document.querySelector('.container-xl.p-responsive').style = 'max-width: 3000px' We then get the private PR rendering more like we'd expect on a non-temporary repo: