#slider_slide1 {
    background-image: url('before_after1.jpg');
}
#slider_slide2 {
    background-image: url('before_after2.jpg');
}
#slider_slide3 {
    background-image: url('before_after3.jpg');
}
#slider_slide4 {
    background-image: url('before_after4.jpg');
}
#slider_slide5 {
    background-image: url('before_after5.jpg');
}