.wave {
    display: inline-block;
}
.wave span {
    display: inline-block;
    animation: wave 3s infinite ease-in-out;
}
@keyframes wave {
    0%   { transform: translateY(0); }
    10%  { transform: translateY(-4px); }
    20%  { transform: translateY(4px); }
    30%  { transform: translateY(-4px); }
    40%  { transform: translateY(4px); }
    50%  { transform: translateY(-4px); }
    60%  { transform: translateY(4px); }
    70%  { transform: translateY(-4px); }
    80%  { transform: translateY(4px); }
    90%  { transform: translateY(-4px); }
    100% { transform: translateY(0); }
}