[Plugin: WordPress Ultra Simple Paypal Shopping Cart] How to add your own "add to cart" ic

same here, I tried to add a custom button url to that class in style.css and I still get the default button with a little piece of my image in front of it.I’ve tried to find classes in Firebug as well but not sure what I’m looking for. has anyone figured this out?

.wp_checkout_button, .wp_cart_button {
     background-image: url('https://www.davehullthehullabalooer.com/button.png'); 

}

produces no result, I tried leaving and removing the button text in settings.

id=”paypalbutton” is what shows in firebug, but

#paypalbutton {
     background-image: url('https://www.davehullthehullabalooer.com/button.png'); 

}

only shows a little piece of my image over the default button image ??