.square {
    width:200px;
    height:200px;
    display:inline-block;
    float: left;
}
.rectangle {
    width:66px;
    height:15px;
    display:inline;
    float: left;
}

#container{
    width:400px;
    height:400px;
    background-color:darkslateblue;
    margin:0 auto;
}
#blockRed{
    background-color: red;
    position: relative;
}

#blockRed3{
    background-color:red;
    position:relative;
}