#container {
    width: 800px;
    height: 800px;
}
.square {
    width: 400px; 
    height: 400px;
    background-color: red;
    display: inline-block;
    float: left;
}
#squareBlue1 {
    background-color: blue;
}
#squareBlue2 {
    background-color: blue;
}

#rectangleRed {
    width: 150px;
    height: 25px;
    background-color: red;
    display: inline-block;
}

#smallblue {
    width: 100px;
    height: 25px;
    background-color: blue;
    display: inline-block;
}

#smallred {
    width: 100px;
    height: 25px;
    background-color: red;
    display: inline-block;
    position: relative;
    
}