Please rotate.

gistfile1.coffee

$('body').bind 'orientationchange', (e) ->
  orientation = if Math.abs(window.orientation) is 90 then 'landscape' else 'portrait'
  $('body').removeClass('portrait landscape')
           .addClass(orientation)
           .trigger('turn', orientation: orientation)

gistfile2.css

 body.landscape::after {
   position: absolute;
   left: 0;
   right: 0;
   top: 0;
   bottom: 0;
   padding: 15%;
   content: "Portrait only mode supported";
   text-align: center;
   font-size: 16px;
   background: rgba(255, 255, 255, 0.9);
 }