Use :host-context and the ::ng-deep selector to apply context-based styling
Often components need to be styled based on the context they are being placed in. In this lesson we will learn about how to apply styles conditionally to our component, based on our ancestor element styles using
:host-context. In the very same way, we also explore how to leverage the
/deep/ shadow DOM selector to target styles to child components.
Note that the ::ng-deep is only a temporary solution and is going to be dropped by Angular once there’s an official standard coming out. As such try to avoid using it.