只保留默认的Struts2主题，它是 xhtml 顺便说一句，只改变你的< s：submit> 和< s：reset> 标签添加到它们主题属性的值简单。

Just leave default Struts2 theme, which is xhtml by the way, as it is and change only your <s:submit> and <s:reset> tags adding to them theme attribute with value simple.

<s:form>
  ... 
  <tr>
    <td colspan="2">
      <s:submit value="Login" theme="simple"/>
      <s:reset value="Clear" theme="simple"/>
    </td>
  </tr> 
</s:form>