.mouse {
    display: inline-block;
    width: 50px;
    height: 80px;
    border: 5px solid #FFF;
    border-radius: 20px;
    text-align: center;
}
    .mouse > .wheel {
        display: inline-block;
        width: 5px;
        height: 15px;
        border: 5px solid #FFF;
        border-radius: 20px;
        margin-top: 10px;
        animation: jumping 1s ease infinite;
    }
@keyframes jumping {
    0% {
        margin-top: 10px;
        opacity: 1;
    }
    100% {
        margin-top: 50px;
        opacity: 0;
    }
}