.swingimage{
    -webkit-transform-origin: 50% 0;
    transform-origin: 50% 0;
    -webkit-animation: swinging 3.5s ease-in-out forwards infinite;
    animation: swinging 3.5s ease-in-out forwards infinite;
}
@-webkit-keyframes swinging{
    0%{-webkit-transform: rotate(10deg);}
    50%{-webkit-transform: rotate(-5deg)}
    100%{-webkit-transform: rotate(10deg);}
}

@keyframes swinging{
    0%{transform: rotate(10deg);}
    50%{transform: rotate(-5deg)}
    100%{transform: rotate(10deg);}
}