.animacion_1{
  transition-duration:2s;
  position:absolute;
    animation-name: example;
    animation-delay: 5s;
    animation-duration: 7s;
    animation-iteration-count: infinite;
    animation-timing-function: linear;
    border-radius: 100%;
}

.animacion_2{
  transition-duration:2s;
  position:absolute;
    animation-name: example;
    animation-delay: 3s;
    animation-duration: 7s;
    animation-iteration-count: infinite;
    animation-timing-function: linear;
    border-radius: 100%;
}

.animacion_3{
  transition-duration:2s;
  position:absolute;
    animation-name: example;
    animation-delay: 9s;
    animation-duration: 7s;
    animation-iteration-count: infinite;
    animation-timing-function: linear;
    border-radius: 100%;
}

@keyframes example {

    0% {transform: scale(0.1)}
    50% {transform: scale(1)}
    100% {transform: scale(.1)}
}