Background image foreground

Hi, I'd like to have my paralaxing background image (of  all sections) in the foreground. With 

body .section-background, .page-section {
    z-index: 10000 !important; 
}

it's in the foreground, but the background-color, too, so that the color covers up all other elements of the site.
How can I just select the (background) img of the .section-background? 

Thanks!