Ionic has made it very easy to develop and test themes for different platforms. Your typical flow is to modify the theme variable in variables.scss first. You should not modify any .css files directly. Also, the Ionic project now makes it safe so that you can't accidentally edit the wrong core theme files, because those core files are no longer in the app folder location.

To update the default color, you just have to modify the color code in variables.scss. You can even add more color names, such as clear: white, and Ionic will automatically take care of the rest. That means the clear keyword is available as a value-to-color attribute on any Ionic element that accepts the color attribute. A few examples are as follows:

<ion-navbar ...