forcing website to show in landscape mode only
<style type="text/css">
#warning-message{
display: none;
}
@media only screen and (orientation:portrait){
#wrapper {
display:none;
}
#warning-message {
display:block;
}
}
@media only screen and (orientation:landscape){
#warning-message{
display:none;
}
}
</style>
....
<div id="wrapper">
<!-- your html for your website -->
</div>
<div id="warning-message">
this website is only viewable in landscape mode
</div>