Captcha Text not Align Center

Question

Captcha text generated by nl.captcha.servlet.CaptchaServlet doesn't allign center.Changing css of tag doesn't work also.Is there any parameter like "align-text"?

<servlet>
        <servlet-name>Captcha</servlet-name>
        <display-name>Captcha</display-name>
        <servlet-class>nl.captcha.servlet.CaptchaServlet</servlet-class>
            <init-param>
            **<param-name>align-text</param-name>
            <param-value>center</param-value>**
        </init-param>
</servlet>