#container {
    background-color: grey; margin: 0 auto;
    width: 400px;
    height: 400px;
}
.square, .circle {
    width: 100px;
    height: 100px;
    display: block;
    float: left;
}

.circle {

    border-radius: 50%;
}

#blockGreen {

    background-color: #01847f;
    position: relative;
}

#blockPink {

    background-color: #f9d2e4;
    position: relative;
}

#blockTexture {
    background-image: url('texture.jpeg');
}