CSS3 pulsating rings

pulse.css

.outer-ring {
    border: 3px solid #999;
    -webkit-border-radius: 30px;
    height: 22px;
    width: 22px;
    position: absolute;
    left:20px;
    top:214px;
    -webkit-animation: pulsate 1s ease-out;
    -webkit-animation-iteration-count: infinite; 
    opacity: 0.0
}

.inner-ring {
    border: 3px solid #999;
    -webkit-border-radius: 30px;
    height: 12px;
    width: 12px;
    position: absolute;
    left:25px;
    top:219px;
    -webkit-animation: pulsate 1s ease-out;
    -webkit-animation-iteration-count: infinite; 
    opacity: 0.0
}

@-webkit-keyframes pulsate {
    0% {-webkit-transform: scale(0.1, 0.1); opacity: 0.0;}
    50% {opacity: 1.0;}
    100% {-webkit-transform: scale(1.2, 1.2); opacity: 0.0;}
}