window.onload = function initialLoad(){   
    updateOrientation();   
}

function updateOrientation(){   
    var contentType = "show_";   
    switch(window.orientation){   
        case 0:   
        contentType += "normal";   
        break;   
  
        case -90:   
        contentType += "right";   
        break;   
  
        case 90:   
        contentType += "left";   
        break;   
  
        case 180:   
        contentType += "flipped";   
        break;   
    }   
document.getElementById("page_wrapper").setAttribute("class", contentType);   
}