With simple steps, you can set colors to your standard UI elements that applies throughout the app. When you need to revert, simply click on 'Restore' button to reinstate the color.
1. Admin > Design > Colors. The 'General' tab is selected by default. Set the general background and font-color of your app.
You can even copy-paste an RGB color code or use it to adjust a selected color.
2. Move on to the 'Popups' tab. You can set the color for each of your UI elements here.
Use the color drop-down box to adjust the color as you would like, and copy-paste an RGB color.