#logo_img {
    background-image: url("/web/Content/society/sawy/images/header_logo.png");
    background-repeat: no-repeat;
    background-size:contain;
    width: 238px; /*or your image's width*/
    height: 75px; /*or your image's height*/
    margin: 0;
    padding: 0;
}

.main-background {
    background: url('/web/Content/society/sawy/images/site_background.png') no-repeat;
    background-size: cover;
    background-position: center;
}

@media only screen and (max-width:1200px) and (min-width:601px) {
    .main-background {
        background: url("/web/Content/society/sawy/images/site_bg_w1200.jpg") no-repeat top center fixed;
        background-size: cover;
    }
}

@media only screen and (max-width:600px) and (min-width:415px){
    .main-background {
        background: url("/web/Content/society/sawy/images/site_bg_w600.jpg") no-repeat top center fixed;
        background-size: cover;
    }
}

@media only screen and (max-width:414px) {
    .main-background {
        background: url("/web/Content/society/sawy/images/site_bg_w414.jpg") no-repeat top center fixed;
        background-size: cover;
    }
}