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