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 smooth scrolling for clicking sidebar links and 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👀

bandicam.2024-12-27.20-06-40-739.mp4

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

[Wulian233]

@hugovk Friendly ping request for review, thank you!

[ezio-melotti]

Thanks for the PR!
It seems that this includes 3 changes:

• The smooth scrolling -- this looks ok to me.
• The sidebar animation -- from the video it looks like it has some issues, with the gray button lagging behind the rest when it's expanded. If this is fixed it might be ok to add it.
• A fade-in animation on the page -- I haven't seen this in action, but it seems somewhat unnecessary.

[Wulian233]

• The sidebar animation -- from the video it looks like it has some issues, with the gray button lagging behind the rest when it's expanded. If this is fixed it might be ok to add it.

Thanks for the reminder, there is now a bug where the sidebar button is seen as part of the sidebar, causing it to be displayed at the end (lag) during the expanded animation. It should be pinned (split) out. I'll fix it tomorrow :)

[Wulian233]

@ezio-melotti I've done the fix, and I've updated the preview video above to show the effect of the changes made by this PR🎉