You can do the following:
$vertical: 'max-height' 50em;
.item {
@include breakpoint($vertical) {
font-size: 2em;
}
}
You can also include height queries with other queries as follows:
$mixed: 15em ('max-height' 50em);
.item {
@include breakpoint($mixed) {
font-size: 2em;
}
}