Slider/separator in the Animation window is not Light theme friendly when the Editor’s theme is set to Light

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. Observe the Animation window

Actual results: The Animation window has a slider in the middle that is not Light theme friendly

Expected results: The slider is Light theme friendly

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