You should be able to nest @media rules this way in CSS3, but it isn’t yet supported by most browsers. See this answer for details.
You would have to fully expand and repeat the top-level media queries for the inner rules for it to work across browsers (and I imagine the SCSS processor would generate something similar):
@media only screen
and (min-device-width: 320px)
and (max-device-width: 480px) {
/* Code for both portrait and landscape */
}
@media only screen
and (min-device-width: 320px)
and (max-device-width: 480px)
and (orientation: portrait) {
/* Code for just portrait */
}
@media only screen
and (min-device-width: 320px)
and (max-device-width: 480px)
and (orientation: landscape) {
/* Code for just landscape */
}