This file can only be included in your app once!

styles.scss

@import './styles/theme';

// Include the base styles for Angular Material core. We include this here so that you only
// have to load a single css file for Angular Material in your app.
// Be sure that you only ever include this mixin once!
@include mat-core();

// Include theme styles for core and each component used in your app.
// Alternatively, you can import and @include the theme mixins for each component that you are using.
@include angular-material-theme($app-theme);

html {
...