html5新增属性

<style type="text/css">form{width: 100%;min-width: 400px;max-width: 800px;margin: 0 auto;font-size: 13px;}input{display: inline-block;width: 100%;height: 40px;margin: 10px 0px;}</style>

<form><fieldset><legend>新增表单属性</legend><label>用户名:<input type="text" name="uname" autofocus="autofocus"  required="required" placeholder="用户名格式:李四" autocomplete="off"/></label><input type="submit" value="提交" /></fieldset></form>