Scroll buttons

So,

Not sure what happened here but the scroll buttons seem to be broken? They work, but the image is not what it was originally. I never messed with the buttons as they are parts of Gantry 5’s theme. Could someone tell me what the cause could be and maybe how to fix it? I removed buttons that scroll through different pictures up top so its not location specific. This is how to button looks. If you cant see the button look at the leg of the guy riding the oxen.

The page I need help with: [log in to see the link]