I am a big fan of dark themes for my code editor. I think that makes my eyes feel more conformable.
There are a lot of pre-defined color themes in this wiki page: Syntax highlighting custom color themes. In this blog, I will show how to use these themes in Code::Block under different platforms (Windows/Linux/Mac).
Download the Download the colour_themes.conf file.
For Windows, make sure Code::Block is closed, and then run cb_share_config.exe. It should be under the folder where you install Code::Block. Load colour_themes.conf on your left and default.conf on your right. Select the themes that you want to import to Code::Block by clicking the check boxes on the left and then select Transfer>>> and Save. I will recommend selecting them all.