Description

Picker's buttons are lost and gets deformed when a specific cosmetic filter is added as discussed in https://github.com/orgs/uBlockOrigin/teams/ublock-issues-volunteers/discussions/234

A specific URL where the issue occurs

www.google.com

Steps to Reproduce

• Add google.com##div:nth-of-type(2) > div

• Navigate to https://google.com

• Invoke picker by right click and select Block Element

Expected behavior:

Picker doesn't lose its buttons and get deformed.

Actual behavior:

Picker loses its buttons and gets deformed.

Your environment

• uBlock Origin version: 1.29.1b8
• Browser Name and version: Firefox 81
• Operating System and version: Win 10