Animation window icon does not properly change when the Editor theme is changed making it difficult to see

Steps to reproduce:

1. Create a new project using the Universal 3D template
2. Make sure the Editor theme is set to Light
3. Open the Animation window (Window > Animation > Animation)
4. Dock the Animation window
5. Change the Editor theme to Dark (Unity > Settings > General > Editor Theme)
6. Observe the Animation window icon
7. Close the Animation window
8. Repeat steps 3 and 4
9. Change the Editor theme to Light (Unity > Settings > General > Editor Theme)
10. Repeat step 6

Actual results: In both Editor theme cases the Animation window icon is hard to see since it did not properly update with the theme change

Expected results: The Animation window icon is changed according to which Editor theme was chosen

Reproducible with versions: 6000.5.0a7

Not reproducible with versions: 6000.0.68f1, 6000.3.10f1, 6000.4.0b9, 6000.5.0a6

Tested on (OS): MacOS Silicon Tahoe 26.2, Ubuntu 24.04

Notes:

• Reopening the window fixes the icon