:popover-open CSS pseudo-classThe :popover-open CSS pseudo-class represents a popover element (i.e., one with a popover attribute) that is in the showing state. You can use this to apply style to popover elements only when they are shown.
:popover-open {
/* ... */
}By default, popovers appear in the middle of the viewport. The default styling is achieved like this in the UA stylesheet:
[popover] {
position: fixed;
inset: 0;
width: fit-content;
height: fit-content;
margin: auto;
border: solid;
padding: 0.25em;
overflow: auto;
color: CanvasText;
background-color: Canvas;
}To override the default styles and get the popover to appear somewhere else on your viewport, you could override the above styles with something like this:
:popover-open {
width: 200px;
height: 100px;
position: absolute;
inset: unset;
bottom: 5px;
right: 5px;
margin: 0;
}popover HTML global attribute