How to include global styles in custom angular library

Question

I have a running Angular 7 application and I am trying to create custom control library.I have some global styles that needs to be imported into the Angular application from this control library.

I am trying to achieve something like the following:

@import "~@angular/material/prebuilt-themes/indigo-pink.css";

in the consumer application where this control library will be used. I have a root style sheet which imports other mixins as shown below:

root.scss

      @include list-themeable($theme);
      @include radiobutton-themeable($theme);
      @include checkbox-themeable($theme);

I need to compile this root.scss file during the library build to create a css file that could be imported in the consumer application where this library will be used.

I googled for the solution and came across Compiling css library in Angular 6:

• Install some devDependencies in our library in order to bundle the css:

   ng-packagr 
   scss-bundle 
   ts-node 
  

• Create a css-bundle.ts

• Add _theme.scss inside the /src directory of the library that actually contains and imports all the css that we want to bundle.

• Add postbuild npm script to run the css-bundle.ts:

• Include it in the styles tag in your Application in the angular.json

Is there any other way to do it..?

Please help me on this.