Yes, sorry, I should have posted here again. I did try clearing my cache, even tried it on a completely different computer where I had never viewed the site before. I don't know what the issue is, but maybe I'm just misunderstanding something. I thought image buttons could override css buttons the way I mentioned in my first post, but it never worked. Anyways, I finally just had to change the code in tpl_product_info_display.php from this:
$the_button = '<input type="hidden" name="cart_quantity" value="1" />' . zen_draw_hidden_field('products_id', (int)$_GET['products_id']) . zen_image_submit(BUTTON_IMAGE_IN_CART, BUTTON_IN_CART_ALT);
} else {
// show the quantity box
$the_button = PRODUCTS_ORDER_QTY_TEXT . '<input type="text" name="cart_quantity" value="' . (zen_get_buy_now_qty($_GET['products_id'])) . '" maxlength="6" size="4" /><br />' . zen_get_products_quantity_min_units_display((int)$_GET['products_id']) . '<br />' . zen_draw_hidden_field('products_id', (int)$_GET['products_id']) . zen_image_submit(BUTTON_IMAGE_IN_CART, BUTTON_IN_CART_ALT);
}
to this:
$the_button = '<input type="hidden" name="cart_quantity" value="1" />' . zen_draw_hidden_field('products_id', (int)$_GET['products_id']) . '<input type="image" class="cartAddButton" src="/includes/templates/custom/buttons/english/button_in_cart.gif" />';
} else {
// show the quantity box
$the_button = PRODUCTS_ORDER_QTY_TEXT . '<input type="text" name="cart_quantity" value="' . (zen_get_buy_now_qty($_GET['products_id'])) . '" maxlength="6" size="4" /><br />' . zen_get_products_quantity_min_units_display((int)$_GET['products_id']) . '<br />' . zen_draw_hidden_field('products_id', (int)$_GET['products_id']) . '<input type="image" class="cartAddButton" src="/includes/templates/custom/buttons/english/button_in_cart.gif" />';
}