::part()

The ::part CSS pseudo-element represents any element within a shadow tree that has a matching part attribute.

custom-element::part(foo) {
  /* Styles to apply to the `foo` part */
}

Syntax

::part( <ident>+ )

Examples

HTML

<template id="tabbed-custom-element">
  <style>
    *,
    ::before,
    ::after {
      box-sizing: border-box;
      padding: 1rem;
    }
    :host {
      display: flex;
    }
  </style>
  <div part="tab active">Tab 1</div>
  <div part="tab">Tab 2</div>
  <div part="tab">Tab 3</div>
</template>

<tabbed-custom-element></tabbed-custom-element>

CSS

tabbed-custom-element::part(tab) {
  color: #0c0dcc;
  border-bottom: transparent solid 2px;
}

tabbed-custom-element::part(tab):hover {
  background-color: #0c0d19;
  border-color: #0c0d33;
}

tabbed-custom-element::part(tab):hover:active {
  background-color: #0c0d33;
}

tabbed-custom-element::part(tab):focus {
  box-shadow: 0 0 0 1px #0a84ff inset, 0 0 0 1px #0a84ff,
    0 0 0 4px rgba(10, 132, 255, 0.3);
}

tabbed-custom-element::part(active) {
  color: #0060df;
  border-color: #0a84ff !important;
}

JavaScript

let template = document.querySelector("#tabbed-custom-element");
globalThis.customElements.define(
  template.id,
  class extends HTMLElement {
    constructor() {
      super()
        .attachShadow({ mode: "open" })
        .append(template.content);
    }
  }
);

Result

Specifications

Specification
Unknown specification
# part

Browser compatibility

BCD tables only load in the browser

See also