我正在玩最近添加的angular.js动画功能，但这并不能正常工作

<style>
    .myDiv{
        width:400px;
        height:200px;
        background-color:red;
    }
    .fadeIn-setup,.fadeOut-setup {
      -webkit-transition: 1s linear opacity;
      -moz-transition: 1s linear opacity;
      -o-transition: 1s linear opacity;
      transition: 1s linear opacity;
    }
    .fadeIn-setup{
      opacity:0;
    }
    .fadeOut-setup{
      opacity:1;
    }
    .fadeIn-setup.fadeIn-start {
      opacity: 1;
    }
    .fadeOut-setup.fadeOut-start{
        opacity:0;
    }
</style>

<div ng-app>
    <div ng-controller='ctrl'>
       <input type='button' value='click' ng-click='clicked()' />  
       <div ng-show="foo == true"  class='myDiv' ng-animate="{show: 'fadeIn', hide:'fadeOut'}">
       </div>
     </div>
</div>

function ctrl($scope){
    $scope.foo = false;
    $scope.clicked = function(){
       $scope.foo = !($scope.foo);
    }
}

http://jsfiddle.net/Kx4TS/1

它会破坏myDiv上的内容，dom.ready并使其逐渐消失。最初应将其隐藏。如何解决？