:open

A pseudo-class that matches elements when they are in an 'open' state, such as a <dialog> or <details> element. It's designed to provide a unified way to style openable components.

This is an experimental technology. The syntax and behavior are still subject to change.

/* Usage Example */
dialog:open {
  /* Styles the dialog when it is visible and open */
  border: 5px solid var(--accent);
  box-shadow: 0 10px 30px rgba(0,0,0,0.5);
}
Limited availability Since 2020 0% global usage

This feature is not Baseline because it does not work in some of the most widely-used browsers.

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