#container {
    background-color: orange;
    margin: 0px auto;
    padding: 0px;
    width: 400px;
    height: 400px;
}
.square, .circle {
    width: 100px;
    height: 100px;
    display: inline-block;
}
.circle {
    border-radius: 50%;
}

#blockRed {
    background-color: rgba(255, 0, 0, 0.466);
    position: relative;
}
#blockBlue {
    background-color:rgb(0, 255, 242);
    position: relative;
}