fix: background color for hover and selected elements in the sidebar …

[IamGianluca]

…is properly displayed

This PR fixes an issue where the background color for elements in the sidebar does not respect the theme.

Without this fix:

With this fix:

In this PR I've only fixed the main theme. I'll also fix the other two themes, but I wanted some feedback since I'm new to GTK theming, and perhaps there is a better way of accomplishing what I did. The changes I made are a departure from the standard @define-color <variable name> <hexadecimal color>;. Are you okay with this?

[IamGianluca]

I've updated also the other two themes.

[IamGianluca]

One more update: I figured out how to set the color for the background when hovering over using the hex format instead of rgba. rgba(196, 167, 231, 0.2) is equal to #c4a7e7 with 0.2 opacity. However, background and foreground colors become semi-transparent when using the latter format in CSS, so you can't read the text. The solution was to use the equivalent format #c4a7e733.

I've updated the PR to keep the code more consistent.

[IamGianluca]

@ThatOneCalculator let me know if you have any feedback

[IamGianluca]

Hi, apologies for bringing attention to the PR after one month. Would it be possible to merge it? I use this GTK theme on multiple machines and would love to use this repo instead of my fork. I think most users would also benefit from having the sidebar display the correct colors.

Many thanks and thank you again for your work! I love the rose-pine eco-system :-)