Improve Existing Dark Themes

[Hexman768]

Description

I think we should have two selectable default themes before we go into creating a full-blown style configurator.

Implementation Ideas

The light theme could just be the current theme of the application, it may just also be called "light (default)" under the dropdown. However, I would like to see the dark theme closer to the Atom One Dark theme in visual studio code. Below I will post a screenshot as an example of what it should be.

Screenshot