css flex realizes that div is fixed in the lower right corner of the browser

css realizes that div is fixed in the lower right corner of the browser

.test{
    
    
  text-align: center;
  width: 20px;
  height: 25px;
  
  position: fixed;
  //当元素之间重叠的时候，z-index 较大的元素会覆盖较小的元素在上层进行显示。
  z-index: 10;
  background-color: #ffffff;
  bottom: 6rem;
  right: 3rem;
  border-radius: 5px;
}