css3 字体自适应

css3提供了一些与当前viewpoint相关的元素，vw，vh，vim等。

“viewpoint” = window size

vw = 1% of viewport width
1vh = 1% of viewport height
1vmin = 1vw or 1vh, 最小
1vmax = 1vw or 1vh, 最大

兼容性：chrome 20+/ safari 6+/ IE 10+ / FF 19+ / IOS 6+

DEMO地址：http://qianduannotes.sinaapp.com/test/fontResize.html  （已经用JS修正重绘bug）

<!DOCTYPE HTML>
<html>
<head>
	<meta charset="UTF-8">
	<title>CSS3 Demo</title>
    <style type="text/css">
        #box { width: 10em; padding: 15px; font-size: 1em;}
        #box2 { font-size: 4vw;}
    </style>
</head>

<body>
    <div id="box">
        我是barret lee 我是barret lee 我是barret lee
    </div>
    <div id="box2">
        我是barret lee 我是barret lee 我是barret lee
    </div>
<script type="text/javascript">
window.onresize = function(){
    var box2 = document.getElementById("box2");
    box2.style["z-index"] = 1;
}
</script>
</body>
</html>