Theme tweaks

Hey Aditia, very nice work on the theme! It's really easy on the eyes. I like it a lot. After trying it out I made a few adjustments for my preferences. Feel free to ignore if you don't like them :)

Adjusted colors for:

- Non-selected objects, making them more subtle
- Made selected objects a bit more yellow for a consistent color palette
- Made "Boxes" shade down rather than up, making them appear more inset since they "hold" items"
- Made pop-up menus a bit lighter as they were blending into the 3D View too much, making them hard on the eyes.