How to multiple class add on contact form 7 submit button : <p>When i add bootstrap button class, like..</p>

<pre><code>[submit class:btn btn-main btn-lg "Send"]
</code></pre>

<p>on browser i see it show only one class add.</p>

<pre><code>&lt;input class="wpcf7-form-control wpcf7-submit btn" &gt;
</code></pre>

<p>I need others 2 class add also Help Me..</p>
