We did a quick fix for max-width issues in T137425: Set a max-width for Special:Notifications page (via T138433: Notifications page: Notification bodies are not truncated), but that doesn't adapt well for users who zoom in.
A single Ctrl-+ will extend the edge outside of the window, depending on screen/window size.
When we do the more comprehensive fix for max-width, zooming should be accounted for.

See also: T139525: Make mobile-friendly version of the Notifications page left nav