.comp-clean {
    background: url(img/comp-cleaning.jpg) center center no-repeat;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover
}

.comp-xray {
    background: url(img/comp-xray.jpg) center center no-repeat;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover
}

.comp-exam {
    background: url(img/comp-exam.jpg) center center no-repeat;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover
}