html, body {
    font-family: Arial, Helvetica, sans-serif;    

}

h1 {
    background-color: #FFAAFF;
}


div#gruen {                                         /* div kann weggelassen werden */
    background-color: #8FE4B3;
    width: 250px;
    float: left;
}

div#blau {
    background-color: #55D4FF;
    margin-left: 260px;
}

div#gelb {
    /* display: block; */
    background-color: #FFFFAA;
    clear: left;
}