Compatibility issues for css in **firefox** header of the active fluent tab doesn't get bold

[jobouillon]

In the current version 4.11.3 (and previous versions as well), some CSS styles are not applied correctly in Firefox. For example, the header of the active Fluent tab is not displayed in bold (font-weight: 600).

You can reproduce this issue using Firefox and the demo page:
Fluent UI Blazor Tabs Demo

We found that the font-variation-settings CSS attribute appears to be affecting this styling.

To fix the issue, we applied the following CSS to the element of the Fluent tab title:

font-variation-settings: normal !important;

This change resolved the problem.

[MarvinKlein1508]

@jobouillon I can confirm this as well. I've create PR #3280 to fix this :)