<form action="job/login.php" method="post">
<div>
学号：<input name="username" type="text" id="username" size="12" class="inputlogin" />
密码： <input name="password" type="password" size="12" class="inputlogin" />
<input name="submit_login" type="submit" id="submit_login" class="submit_login" value=" 登 陆 " />
</div>
</form>

好象加个 <div> </div> 或则 <p></p> 就OK了