:active

Since UXP v3.0

Matches when the selected element is active. An element is considered to be active when the user is actively clicking on the element.

See: https://developer.mozilla.org/en-US/docs/Web/CSS/:active

Example:

p:active {
    background-color: yellow;
}

Quirks and Exceptions

• An element that is being right-clicked is considered "active".
• Double-clicking an element will cause it to be unable to be considered "active" until the double-click detection timer expires.