Change z-index value (labels shown over menu)

Hello,

I need to find the proper code for changing the z-index value to hide my labels behind the menu. Now are displayed above the menu layer (see URL)

I have tried to put this into the CSS form of the plugin, but it did not work

.product .images {position: relative;}
html .br_alabel_image {
    z-index: 10;
}

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