hover opacity only if links present

Hello everyone,

I would need hover opacity effect on navigation buttons like here:
http://klarakolonits.com/award-of-excellence-nivodij/

But with the code I was advised to add in custom css when I asked on a general forum, which is the below, I basically get hover effect on ALL images which is not what I want, not all of them have links or need hover effects, this is the code:

`.entry-content .aligncenter, .main .aligncenter [class*=wp-image]:hover {
opacity: 0.5;
}`

I tried also to add the image title and class id in the image menu of the two buttons and the following code to custom css but no effect

#whatever .x-img:hover {
  opacity: 0.5;
}

Any tips? Let’s say I would be happy if the hover effect appeared on hyperlinked pics or only the selected ones with selected ids, whatever option is fine. Thank you!