<div class=box1></div>

.box1{
    width:100px;
    height:100px;
    margin:auto;
    animation:myMove .5s infinite alternate linear;
    -moz-animation:myMove .5s infinite alternate linear;
    -webkit-animation:myMove .5s infinite alternate linear;
    -o-animation:myMove .5s infinite alternate linear;
}
@keyframes myMove{
    0%{transform:scale(.7)
    100%{transform:scale(1)
}
@-moz-keyframes myMove{
    0%{transform:scale(.7)
    100%{transform:scale(1)
}
@-webkit-keyframes myMove{
    0%{transform:scale(.7)
    100%{transform:scale(1)
}
@-o-keyframes myMove{
    0%{transform:scale(.7)
    100%{transform:scale(1)
}