SASS mixin stuff

// previously-defined @mixin dimensions($width, $height) …
// previously-defined @mixin spacing($margin, $padding) …

div {
    @include dimensions(100px, 10px) // (width, height)
    @include spacing(0, 13px 0 7px 0) // (margin, padding)
}

// generated CSS:

div {
    width: 100px;
    height: 80px;
    margin: 0;
    padding: 0;
}