Add animations to the sidebar and other small places

[Wulian233]

I hope this theme isn't too stiff, let's make it more visually appealing :)

Added animations for showing/hiding the sidebar Color transition for sidebar buttons

It shouldn't affect normal usage, but it will make it more user-friendly👀

https://github.com/user-attachments/assets/ac0bd262-425a-454f-b338-a7eb8383e28e

The video has been compressed, so the animation might not look very smooth.