The popup-position property allows to define explicitly position of the popup element in respect of position of its anchor element ( element to what the popup belong to).

The popup-position CSS property accepts one of followng formats:

Where:

<popup-reference-point> and <anchor-reference-point> are enumeration values:

Example, this declaration:

select > popup {
popup-position: top-right bottom-right;
}

will position the popup element in the way that its top-right corner is placed at bottom-right corner of the anchor element (the select itself here).