Angular's emulated encapsulation mode supports a custom pseudo class, `::ng-deep`.

**The Angular team strongly discourages new use of `::ng-deep`**. These APIs remain

When a selector contains `::ng-deep`, Angular stops applying view-encapsulation boundaries after that point in the selector. Any part of the selector that follows `::ng-deep` can match elements outside the component’s template.

For example:

- a CSS rule selector like `p a`, using the emulated encapsulation, will match `<a>` elements that are descendants of a `<p>` element,

both being within the component's own template.

- A selector like `::ng-deep p a` will match `<a>` elements anywhere in the application, descendants of a `<p>` element anywhere in the application.

That effectively makes it behave like a global style.

- In `p ::ng-deep a`, Angular requires the `<p>` element to come from the component's own template, but the `<a>` element may be anywhere in the application.

So, in effect, the `<a>` element may be in the component's template, or in any of its projected or child content.

- With `:host ::ng-deep p a`, both the `<a>` and `<p>` elements must be decendants of the component's host element.

They can come from the component's template or the views of its child components, but not elsewhere in the app.