@media (min-width: 1200px) {
    #intro {
        background: url('/Images/bgtransgrad-500.png') no-repeat left center, 
                    url('/Images/IntroBack/statistics-full.jpg') no-repeat right center; 
    }
}
@media (min-width: 980px) and (max-width: 1199px) {
    #intro {
        background: url('/Images/bgtransgrad-500.png') no-repeat left center, 
                    url('/Images/IntroBack/statistics-1200.jpg') no-repeat right center; 
    }
}
@media (min-width: 768px) and (max-width: 979px) {
    #intro {
        background: url('/Images/bgtransgrad-250.png') no-repeat left center, 
                    url('/Images/IntroBack/statistics-980.jpg') no-repeat right center; 
    }
}
@media (max-width: 767px) {
    #intro {
        background: url('/Images/bgtransgrad-150.png') no-repeat left center, 
                    url('/Images/IntroBack/statistics-770.jpg') no-repeat right center; 
    }
}