body {
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

#challenge22 ul{
    display: flex;
    justify-content: space-between;
    position: relative;
    list-style-type: none;
}
#challenge22 ul li {
    position: relative;
    border: 1px solid #333;
    margin: 0 10px;
    border-radius: 50%;
    text-align: center;
    color: #333;
    font-size: 30px;
    width: 75px;
    height: 75px;
}
#challenge22 ul li i {
    position: relative;
    z-index: 1;
    transition: 0.5s;
    line-height: 75px;
}
#challenge22 ul li:hover i {
    color: #fff;
}
#challenge22 ul li::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 100%;
    height: 100%;
    border-radius: 50%;
    border: 1px dashed #333;
    animation: circle 10s linear infinite;
    opacity: 0;
    transition: 0.5s;
}

#challenge22 ul li::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 100%;
    height: 100%;
    background-color: #333;
    border-radius: 50%;
    opacity: 0;
    transition: 0.5s;
}

#challenge22 ul li:hover:before {
    width: 90.5%;
    height: 90.5%;
    opacity: 1;
}

#challenge22 ul li:hover:after {
    width: 80%;
    height: 80%;
    opacity: 1;
}

@keyframes circle {
    from {
        transform: translate(-50%, -50%) rotate(0deg);
    } to {
        transform: translate(-50%, -50%) rotate(360deg);
    } 
}