.centerdiv {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%); /* Moves the element back by half its width and height */
    width: 100px;
    height: 100px;
    background-color: lightgreen;
}

.parentContainer {
    height: 100px;
    width: 100px;
    display: flex;
    justify-content: center;
}

.childContainer {
    align-self: center;
}