#intro
{
 background-image: linear-gradient(200deg, #D2BDBD, #c4b9b9);
 margin: 3em 3em 0em;
 padding: 10px;
 border-color: blue;
 border-style: dotted;
}

.falling-link {
  position: absolute;
  width: 20px;
  height: 20px;
  border-radius: 50%;
}

@keyframes falling-1 {
    from {top:0%;}
  to {top:100%;}
}

.falling-link:nth-child(1)
{
    left: 88%;
  animation: 10s ease-in 1s infinite falling-1;
}
.falling-link:nth-child(2)
{
    left: 10%;
  animation: 12s ease-in 1s infinite falling-1;
}
.falling-link:nth-child(3)
{
    left: 35%;
  animation: 9s ease-in 1s infinite falling-1;
}
.falling-link:nth-child(4)
{
    left: 67%;
  animation: 11s ease-in 1s infinite falling-1;
}