Are you really on Lion? For me, it fails because I am on Mavericks. They're using code similar to below, which only matches Lion and Mountain Lion. var ua =

Are you really on Lion? For me, it fails because I am on Mavericks. They're using code similar to below, which only matches Lion and Mountain Lion. var ua = navigator.userAgent || navigator.appVersion; if(ua.match(/10[_.]7/) || ua.match(/10[_.]8/)) console.log("valid os"); You can find the code by viewing the source here: http://paddleover.com/javascripts/application.js http://paddleover.com/javascripts/application.js