html, body{
  margin: 0px;
  padding: 0px;
     

}
.background3{
  position: absolute;
  display: block;
  top: 0px;
  left: 0px;
  z-index: 0;
  position: fixed;
  width: 100vw;
  height: 100vh;
  top: 0;
  left: 0;
  overflow: hidden;
  

}