Why is this not working

Why is this not working

I display my JQuery-UI dialog like this
$("#dlgPassage").dialog({
                width: 490,
                buttons: {
                    "Confirm": {
                        "text": 'Confirm',
                        "click": function () { Click_btnConfirm() },
                        "class": 'myclass'
                    }
                }
            });

I then style myclass by using inline like this. But there is no effect on the confirm button ?
Why is it not working ?
<style>
       .myclass
       {
            background-color: Blue;
       }

//Tony
   
    </style>