为什么纸质项目的内容不是垂直居中于IE，就像Chrome中的示例一样：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>JS Bin</title>
<base href="//polygit.org/components/">
<script src="webcomponentsjs/webcomponents-lite.js"></script>
<link rel="import" href="polymer/polymer.html">
<link rel="import" href="paper-item/paper-item.html">
</head>
<body>
<template is="dom-bind">
<paper-item style='background-color:Red'>Why is this not centered vertically in IE?</paper-item>
</template>
</body>
</html>
http://jsbin.com/busemomecu/1/edit?html,output
干杯