#arrowUp{
  display: none;
  position: fixed;
  bottom: 50px;
  left: 50px;
  border: 4px solid gray;
  border-radius: 10px;
  padding: 10px;
  z-index: 9999999;
  background: white;
}
  
#arrowUp img{
   width: 32px;
}