body {
    background-color: white;
    margin: 0;
    padding: 0;
}

#container {
    position: relative;
    width: 400px;
    height: 400px;
    margin: 100px auto;
}

.square {
    width: 200px;
    height: 200px;
    position: absolute;
}

.red {
    background-color: red;
}

.blue {
    background-color: blue;
}

.rec {
    width: 60px;
    height: 15px;
    position: absolute;
}