Desmos: Tab Number Hard To Read When Not Selected

### Is there an existing issue outlining your problem? - [x] I have searched the existing issues and they do not solve my problem. ### What userstyle are you seeing the problem on? lbl:desmos ### Describe your problem. When not selecting a tab, the number of the tab is hard to read because of how dark it is. ### Attach screenshots. [desmos.png](https://github.com/user-attachments/assets/fb36e973-cdf7-460d-9347-19da863c88bd) ### Browser version(s) this issue occurs on Zen v1.19.8b ### Stylus extension version Stylus 2.3.19 ### Installed version of the userstyle v2026.04.20 ### Any additional comments? _No response_