VisualEditor is removing the font weight from the "article" tab when using Monobook on the English Wikipedia.

Steps to reproduce:

• Go to https://en.wikipedia.org/wiki/Canada_Goose_(clothing)

• Click "edit this page".

• The "article" tab loses its boldness.

• Clicking the "cancel" button does not restore the boldness.

Version: unspecified
Severity: normal