Only applies to top level elements, can't target children of slotted element. One workaround is inserting a style tag into the document that styles special classes you add to your slotted elements (It should be inserted into the body as inserting into the component will disable the slots)

This article explains how you can use the <template> and <slot> elements to create a flexible template that can then be used to populate the shadow DOM of a web component.

The <slot> HTML element is a placeholder inside a Web Component that you can fill with your own markup when the component is used. This lets you create separate DOM trees and present them together.

We can easily style named slots by using syntax slot [name]::slotted (*). But is there any way that we can style default slots because they don't have any name associated?

This article shows you how to use slots to create web components that accept rich content while maintaining clean, declarative markup. You’ll learn how slots work with shadow DOM, how to implement both default and named slots, and how to style slotted content effectively.

This article explains how you can use the <template> and <slot> elements to create a flexible template that can then be used to populate the shadow DOM of a web component.

In order to be portable, Web Components can add default styles for the element itself (also known as the shadow host). They can also style slotted elements with some default styles.

Just because you’re using a web component doesn’t mean the styles of it are entirely isolated. You might have content within a web component that is styled normally along with the rest of your website.

Stencil.js will allow you to use slots without using the shadow dom. It's a feature that I use regularly.

Since slotted elements don't exist in the ShadowDOM to style them require some special selectors in your component internal styles, the ::slotted psuedo selector.