<script>
function orient() {
    switch(window.orientation) {
        case 0:
            document.getElementById("orient_css").href = "css/iphone_portrait.css";
            break;
        case -90:
            document.getElementById("orient_css").href = "css/iphone_landscape.css";
            break;
        case 90:
            document.getElementById("orient_css").href = "css/iphone_landscape.css";
            break;
    }
}
window.onload = orient();
</script>