Dropdown menus overflow screen on mobile and can't be scrolled

[studyingegret]

https://docs.rs/dataview/1.0.2/dataview/

The settings icon:

Mobile view: "Word wrap source code" is clipped off and I can't scroll to show it.

Desktop view:

Similar problem with "Help" dropdown:

[syphar]

cc @GuillaumeGomez ?

[GuillaumeGomez]

Moving to rustdoc and sending a fix today. :)

[GuillaumeGomez]

Opened #151216.