.flotar-animacion
{
    animation-name: flotacion;
    animation-duration: 3s;
    animation-iteration-count: infinite;
    animation-timing-function: ease-in-out;
    margin-left: 30px;
    margin-top: 5px;
}

@keyframes flotacion {
    0% { transform: translate(0,  0px); }
    50%  { transform: translate(15px, 15px); }
    100%   { transform: translate(0, -0px); }  
}