Hey, here is the easiest approach: Mendix comes ready with a highly-configurable theme which gives you a head start in creating your app’s overall look and feel. Configuring the theme settings inside your app’s theme/native/custom-variables.js file in your windows explorer. Edit the text file replacing the color codes as you prefer. For native apps you can configure your dark theme here. Pay attention to switch the mode on your device before testing. Cheers!