When you create a LitElement component, you can apply styles directly inside your component definition using the static styles property. This approach leverages the shadow DOM, which acts as a boundary that encapsulates your component’s styles and markup. As a result, styles defined within a Lit component do not leak out to the rest of the page, nor do external styles affect the component’s internal elements.

The shadow DOM ensures that everything inside your component—structure, styles, and behavior—is scoped and protected from the global document. In the provided example, the .greeting class inside the LitElement is styled with a blue color and bold text, while the same class name outside the component is styled with red and italic text. Because of the shadow DOM, the styles inside the LitElement do not affect the external element, and vice versa.

This encapsulation is a key feature of LitElement. By defining styles using the css template tag and the static styles property, you keep your component’s appearance consistent and isolated, regardless of the page's global styles. This makes LitElement components highly reusable and predictable in any environment.