contact form plugin submit hover button

Hello,

i am currently using the contact form plugin by BestWebSoft. I have been able to change the submit button myself to a different design, but I would like to use CSS image sprites to do a hover state for this. As you can see from my code below I have already set it up the current submit button image to use css sprites, I just haven’t been able to get the hover state to work. I know I need to add in the css background position somewhere, I have tried adding it into the css file in the plugin and my theme but that hasn’t helped.

Thanks ??

$content .= '<div style="text-align: left; padding-top: 8px;">
					<input type="hidden" value="send" name="cntctfrm_contact_action"><input type="hidden" value="Version: 3.26" />
					<input type="submit" value="'. __( "Submit", 'contact_form' ). '" style="cursor: pointer; margin: 0pt; text-align: center;margin-bottom:10px;border:0;background: url(...images/submit.gif) no-repeat 0 0;
	width: 59px;
	height: 20px;
	display: block;
	text-indent: -9999px;" />
				</div>
				</form>';