<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title></title>
<style>
.abc{}
.hou {
  width: 200px;
  height:200px;
  margin: 100px auto;
  background-color:#F9F;
  border-radius:200px;
  -webkit-animation:scaleout 6.0s infinite ease-in-out;
  animation: scaleout 6.0s infinite ease-in-out;
}
@-webkit-keyframes scaleout {
  0% { -webkit-transform: scale(0,0) ;opacity: 0;}

  50% {
    -webkit-transform: scale(1,1);
    opacity:1;
  }
  100% {
    -webkit-transform: scale(0,0);
    opacity: 0;
  }
}
@keyframes scaleout {
  0% {
     transform: scale(0.0);
     -webkit-transform: scale(0.0);
   }
   50%{
       -webkit-transform: scale(1,1);
        transform: scale(1,1);
        opacity:1;
    }
   100% {
    transform: scale(0,0);
    -webkit-transform: scale(0,0);
    opacity:0;
  }
}
</style>
</head>
<body>
<div class="hou"></div>

</body>
</html>