Actions in sidebar has weird border

[MorrisJobke]

• go to user management
• create a group
• assign a user to this group
• click in the sidebar on the group: a trash icon should appear:

cc @skjnldsv

[MorrisJobke]

May be related to nextcloud/calendar#321

[skjnldsv]

This is related to a too much global selector used for the blue shadow.
I'm on it. It's also happening on popovermenu in some case.