#bell {
    position: relative;
    animation-name: shake;
    animation-duration: 0.5s;
    animation-iteration-count: infinite;
}

@keyframes shake {
    0% {
        transform: rotate(0deg);
    }

    10% {
        transform: rotate(15deg);
    }

    20% {
        transform: rotate(30deg);
    }

    30% {
        transform: rotate(45deg);
    }

    40% {
        transform: rotate(30deg);
    }

    50% {
        transform: rotate(15deg);
    }

    60% {
        transform: rotate(-15deg);
    }

    70% {
        transform: rotate(-30deg);
    }

    80% {
        transform: rotate(-45deg);
    }

    90% {
        transform: rotate(-30deg);
    }

    100% {
        transform: rotate(-15deg);
    }
}