#container {
    width: 800px;
    height: 800px;
}
#blockRed {
    width: 400px; 
    height: 400px;
    background-color: red;
    display: inline-block;
    float: left;
    margin: 0px;
}
 #blockBlue{
     width: 400px; 
    height: 400px;
    background-color: darkblue;
    display: inline-block;
    float: left;
    margin: 0px;
}

#rectangleRed1 {
    position: absolute; left: 535px; top: 8px;
    width: 150px;
    height: 25px;
    background-color: red;
    display: inline-block;
}

#rectangleRed2 {
    position: absolute; left: 125px;top: 783px;
    width: 150px;
    height: 25px;
    background-color: red;
    display: inline-block;
}