Backport #24184 by @krzysztofjeziorny
A vertical overflow appears in Firefox 112/MacOS 12.6 when the system
setting for scrollbars is to "Always" show them.
Here, the fixed 100vw container widths are removed, which removes the
overflow. It is, however, only simulated in Developer Tools in latest
Firefox and Chromium, so please test on a Gitea installation.
Co-authored-by: Krzysztof Jeziorny <872730+krzysztofjeziorny@users.noreply.github.com>