Implement this:
Working example: http://jsfiddle.net/Gajotres/PMrDn/53/
HTML:
<input class="validate[required,custom[onlyLetterSp]] text-input" id="first_name" name="firstName" type="text" placeholder="First Name" maxlength="10"/>
Javascript:
$('#first_name').parent().css('border-color','red');