**Steps to replicate the issue** (include links if applicable):
* View a page such as https://en.wikipedia.org/w/index.php?title=Brahmic_scripts&diff=1135922907&oldid=1132384454&diffmode=source&useskin=vector-2022
* Reading mode: https://en.wikipedia.org/wiki/Brahmic_scripts?useskin=vector-2022
**What happens?**:
* Viewing the page requires horizontal scrolling to see the diff and other elements at the top of the page
**What should have happened instead?**:
* The diff area should be constrained to the standard page area, such as was done in Vector and other skins, see vector legacy for comparison: https://en.wikipedia.org/w/index.php?title=Brahmic_scripts&diff=1135922907&oldid=1132384454&diffmode=source&useskin=vector
* In reading mode, the top most content should be constrained to the standard page area as well, example in legacy vector: https://en.wikipedia.org/wiki/Brahmic_scripts?useskin=vector
**Software version** (skip for WMF-hosted wikis like Wikipedia):
* WMF Production
**Other information** (browser name/version, screenshots, etc.):
* Originally reported on enwiki by @CX_Zoom , see https://en.wikipedia.org/w/index.php?title=Wikipedia:Village_pump_(technical)&oldid=1136048313#Stretched_page for info and screenshot