* {
    box-sizing: border-box;
}

.parent {
    width: 800px;
    height: 600px;
    margin: 30px auto;
    padding: 10px;
    display: flex;
    justify-content: space-evenly;
}

.E {
    display: grid;
    width: 325px;
    height: 580px;
    justify-items: center;
    align-content: center;
    border-top: 80px solid #323234;
    border-left: 80px solid #323234;
    border-bottom: 80px solid #323234;
    position: relative;
}

.o1 {
    background-color: #323234;
    width: 100%;
    height: 80px;
}

.E::before {
    content: "";
    background-color: #fea604;
    width: 50.75px;
    height: 50.75px;
    position: absolute;
    left: 177px;
    top: -66px;
    animation-name: move;
    animation-duration: 10s;
    animation-timing-function: linear;
    animation-iteration-count: infinite;
}

@keyframes move {
    0% {
        transform: translate(0, 0);
    }

    20% {
        transform: translate(-238px, 0);
    }

    25% {
        transform: translate(-238px, 250px);
    }

    30% {
        transform: translate(0, 250px);
    }

    35% {
        transform: translate(-238px, 250px);
    }

    40% {
        transform: translate(-238px, 500px);
    }

    45% {
        transform: translate(0px, 500px);
    }

    50% {
        transform: translate(-238px, 500px);
    }

    60% {
        transform: translate(-238px, 0);
    }

    70% {
        transform: translate(0, 0);
    }

    100% {
        transform: translate(0, 0);
    }
}

.L {
    background-color: #fefefc;
    width: 325px;
    height: 580px;
    justify-items: center;
    align-content: center;
    border-left: 80px solid #323234;
    border-bottom: 80px solid #323234;
    position: relative;
}

.L::after {
    content: "";
    background-color: #fea604;
    width: 50.75px;
    height: 50.75px;
    position: absolute;
    right: 15px;
    bottom: -65px;
    animation-name: move1;
    animation-duration: 10s;
    animation-timing-function: linear;
    animation-iteration-count: infinite;
    animation-delay: 7s;
    opacity: 0;
}

@keyframes move1 {
    0% {
        transform: translate(0, 0);
        opacity: 0.9;
    }

    5% {
        transform: translate(-245px, 0);
        opacity: 1;
    }

    15% {
        transform: translate(-245px, -498px);
    }

    20% {
        transform: translate(-245px, -498px);
        opacity: 1;
    }

    30% {
        transform: translate(-245px, -498px);
        opacity: 0;
    }

    100% {
        transform: translate(-245px, -498px);
        opacity: 0;
    }
}