# CSS Shadow Parts - Theme

The ::theme(part) pseudo selector let you style a Shadow Part in every instance it appers on the document, no matter the depth.

<my-app>
  #shadow-root
    <x-element></x-element>
    <x-element></x-element>
</my-app>

my-app::theme(header) { ... }

STATUS: Working Draft

Explainer here.