.bounce {
    animation: bounce 2s infinite;
    -webkit-animation: bounce 2s infinite;
    -moz-animation: bounce 2s infinite;
    -o-animation: bounce 2s infinite;
}

@-webkit-keyframes bounce {
    0%, 20%, 50%, 80%, 100% {-webkit-transform: translateY(0);} 
    40% {-webkit-transform: translateY(-30px);}
    60% {-webkit-transform: translateY(-15px);}
}
 
@-moz-keyframes bounce {
    0%, 20%, 50%, 80%, 100% {-moz-transform: translateY(0);}
    40% {-moz-transform: translateY(-30px);}
    60% {-moz-transform: translateY(-15px);}
}
 
@-o-keyframes bounce {
    0%, 20%, 50%, 80%, 100% {-o-transform: translateY(0);}
    40% {-o-transform: translateY(-30px);}
    60% {-o-transform: translateY(-15px);}
}
@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {transform: translateY(0);}
    40% {transform: translateY(-30px);}
    60% {transform: translateY(-15px);}
}