.

@media only screen and (min-width: 768px) {
    /* tablets and desktop */
}

@media only screen and (max-width: 767px) {
    /* phones */
}

@media only screen and (max-width: 767px) and (orientation: portrait) {
    /* portrait phones */
}

@media only screen and (max-width: 600px) and (min-width: 400px)  {
/* between sizes */
}

/* No greater than 900px, no less than 400px */
@media (max-width:900px) and (min-width:400px) {
    .foo {
        display:none;
    }
}