img { max-width: 100%; }

.imagen_drop {
    border: solid;
    margin: 1px;
    height: 64px;
}

.imagen_drop_max {
    border: solid;
    margin: 1px;
    max-width: 90%;
    max-height: 90%;
}

#logo {
    text-align: center; 
    position: absolute; 
    margin: 0 auto; 
    display: inline-table;
}