:hostfunction

Used inside a Shadow DOM to style the 'host' element (the custom element itself). The functional version ':host()' lets you apply styles only if the host matches a specific selector.

/* Usage Example */
:host(.dark-mode) {
  background-color: #333;
  color: white;
  /* styles the custom element only when it has the 'dark-mode' class */
}
Widely available Since 2020 95% global usage

This feature is well established and works across many devices and browser versions. It has been available across browsers since 2020.

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