​x
 
<!DOCTYPE html>
<html>
<head>
<style>
:popover-open {
  width: 150px;
  height: 150px;
  position: absolute;
  inset: unset;
  bottom: 25px;
  left: 25px;
  margin: 0;
  color: maroon;
  background-color: orange;
  font-size: 25px;
}
</style>
</head>
<body>
​
<h1>:popover-open 演示</h1>
​
<button popovertarget="myPopover">打开弹出框</button>
​
<div popover id="myPopover">你好！</div>
​
</body>
</html>
​