app.css (or app.scss)

The app.css (or app.scss) file contains the global styles for the app. The name of the file is important, since this file is automatically loaded when the app starts.

Platform specific styles ​

Platform specific styles can be defined in app.<platform>.(css|scss)

Using a different file name or location ​

Using CSS ​

Using Sass ​

Using other css preprocessors ​