html5 – webkit转换在Safari上打破z-index

我试图让一层似乎像一面墙掉下来,露出了它后面的一层.我设置了两个固定的div位置. “Wall”div的z-index为9999,“Background”div的z-index为0;

在我测试的Webkit浏览器(Safari / IOS)中,似乎一旦动画在“墙”上开始,z索引丢失或忽略,导致“墙”图层突然消失在背景div后面.

关于如何保存层的z-索引的任何想法？提前致谢！

示例代码
(注：jsfiddle在底部)

HTML代码

<div id="wall">
    This is the wall
</div>

<div id="background">
    This is the background
</div>

<button id="start" style="float: right;">
Flip Down
</button>

一些javascript启用按钮

$('#start').click(function(){
    alert('Should Fall Down like a wall,revealing the background');
    $('#wall').addClass('animated flipDown');
});

CSS代码(从animate.css下载)

#wall{
    background-color: #F00;
    width: 100px;
    height: 100px;
    position:fixed;
    top:0;
    left:0;
    z-index: 9999;
}

#background{
    background-color: #00F;
    width: 100px;
    height: 100px; 
    position:fixed;
    top:0;
    left:0;
    z-index: 0;
}

.animated {
  -webkit-animation-duration: 1s;
  animation-duration: 1s;
  -webkit-animation-fill-mode: both;
  animation-fill-mode: both;
}


/*** flipDown ***/

@-webkit-keyframes flipDown {
  0% {
    -webkit-transform: perspective(400px) rotateX(0deg);
    transform: perspective(400px) rotateX(0deg);
    -webkit-transform-style: flat;
    opacity: 1;
  }

  100% {
    -webkit-transform: perspective(400px) rotateX(90deg);
    transform: perspective(400px) rotateX(90deg);
    -webkit-transform-style: flat;
    opacity: 1;
  }
}

@keyframes flipDown {
  0% {
    -webkit-transform: perspective(400px) rotateX(0deg);
    -ms-transform: perspective(400px) rotateX(0deg);
    transform: perspective(400px) rotateX(0deg);
    opacity: 1;
  }

  100% {
    -webkit-transform: perspective(400px) rotateX(90deg);
    -ms-transform: perspective(400px) rotateX(90deg);
    transform: perspective(400px) rotateX(90deg);
    opacity: 0;
  }
}

.flipDown {
    -webkit-animation-name: flipDown;
    animation-name: flipDown;
    -webkit-backface-visibility: visible !important;
    -ms-backface-visibility: visible !important;
    backface-visibility: visible !important;
    -webkit-transform-origin: bottom;
    -ms-transform-origin: bottom;
    transform-origin: bottom;
}

的jsfiddle

http://jsfiddle.net/3mHe2/2/

查看Safari与Chrome的区别.