<style type="text/css">
    @media screen{
        body{
            background: green;
        }
    }
    @media handheld{
        body{
            background: red;
        }
    }
</style>

@media screen and (min-width: 700px){
    body{
        background: green;
    }
}
@media screen and (max-width: 600px){
    body{
        background: red;
    }
}