.square, .circle {
    width: 100px;
    height: 100px;
    display: inline-block;
    float: right;
}
.circle {
    border-radius: 50%;
}
#blockRed {
    background-color:aquamarine ;
}
#blockYellow {
    background-color: yellow;
}
#container {
    background-color: aqua;
    margin: 0 auto;
    height: 400px;
    width: 400px;
}