<html>
<head>
<meta charset="utf-8">
<title>搜索框</title>
<style>
#demo{background-color:rgba(125,125,125,0.2); height:45px; width:300px;}</style>
</head>
<body>
<p>WWF's goal is to:
<q>Build a future where people live in harmony with nature.</q>
<!--q标签添加双引号-->
We hope they succeed.</p>
<form action="" id="demo">
<input type="text" placeholder="搜索......." style="margin:3px;border:1px solid gray;border-radius:2px;width:290px;height:36px;">
</form>
</body>
</html>
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原文：http://blog.51cto.com/13400327/2055760