请教一下， 这个span怎么就换行了呢
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
</head>
<body>
<form class="pass_reg_form" id="pass_reg_form" action="" method="post">
<p class="pass_reg_p_email" id="pass_reg_p_email">
<label class="pass_reg_label_email" id="pass_reg_label_email">My e-mail address: </label>
<input class="pass_reg_input_email" id="pass_reg_email" type="text" name="email" autocomplete="off" tabindex="1"/>
<span class="pass_reg_err_email" id="pass_reg_email_err" style="display:block">Please enter an email address</span>
</p>
</form>
</body>
</html>
