.graphic_wrapper {
    float:left;
    width:100%;
    margin-bottom: 20px;
    margin-top:20px;
}

.graphic_container {
    width:100%;
    max-width:460px; 
    float:none;
    margin:auto;
}

.graphic {
    width:100%;
}

@media all and (max-width: 640px) {
    .graphic_container {
        max-width:350px; 
    }
}