CSS 破碎文字效果

PHP:

<style type="text/css">
h2 {
    font:3em/1em "黑体","宋体",serif;
    font-weight: bold;
    margin:0;
    position: relative;
    overflow: hidden;
    float: left;
}
h2 span {
    position: absolute;
    width: 100%;
    height: 1em;
    background: url(attachments/month_0512/bg.gif);
}
p {
    clear: left;
}
</style>
<h2><span></span>这是文字，不是图片哦</h2>
<p>上面是文字，不是图片哦</p>