[Bug]: User avatar outline is clipped on mobile when menu is open

Bug description

On mobile devices, the circular white outline around the user avatar in the top-right corner gets visually clipped on the left and right sides when the avatar menu is open. This only occurs on mobile, not on desktop (even when simulating narrow viewport).

📱 Devices tested

• iPhone (Safari)
• iPhone (Chrome)
• No browser extensions or custom CSS
• Clipping does not occur on desktop, even in responsive/narrow viewport mode <---------EDIT!

-------> It does clip on desktop at the narrowest screen view in my browsers.

💡 Notes

• The bug is purely visual, not functional.
• The hover/focus state works correctly on desktop.
• Removing all custom CSS had no effect — bug persists on a clean default theme.

This may be a CSS overflow: hidden or margin/padding issue on a container.

Steps to reproduce

• Open Nextcloud in a mobile browser (tested on Safari and Chrome).
• Tap the round user avatar icon in the top-right to open the account menu.
• Observe the circular white outline around the icon.
• Notice that the left and right sides of the circle are slightly clipped.

Expected behavior

The circular outline around the avatar icon should be fully visible on all sides, regardless of device or viewport.

Nextcloud Server version

31.0.4

PHP engine version

PHP 8.3

Web server

Apache (supported)

Is this bug present after an update or on a fresh install?

Fresh Nextcloud Server install

Start by reproducing the clipping from the top-right user avatar entry point in a mobile or narrow viewport with the account menu open. Trace the avatar outline and its surrounding containers in the frontend styles, then verify that the full circular outline is visible on both sides without changing desktop behavior.