part and replace it with a normal submit button, like this
<a class="button" onClick="contact_send();">
<span class="button-icon"><img alt="" src="assets/img/icon/mail.png"></span>
<span class="button-text">Send it!</span>
Your form should now be submitted to contact.php and processed (if there is something in contact.php that can process).
<input type="submit" name="submit" value="send it">