#grasses-drawing {
    margin-top: 1em;
    text-align: center;
}
#grasses-drawing img {
    /* /images/grafs/2011/grasses.png */
    width: 600px;
    height: 420px;
}
@media only screen and (max-width: 650px) {
    #grasses-drawing img {
        width: 100%;
        height: auto;
    }
}