.clock {
    width: 300px;
    height: 110px;
    position: absolute;
    margin:  -20px 51%;
    overflow: hidden;
    z-index: 100;
}

#pendulum {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 50%;
    transform: translateX(-50%);
    animation: swing 4s ease-in-out infinite;
    transform-origin: top center;
}

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