.banner-block 
{
   display: flex;
   flex-wrap: wrap;
   height: auto;
}

.single-banner {
    display: block;
    min-width: 250px;
    height: 100px;
    background-position: center;
    background-size: cover;
    margin: 5px 15px;
}
.single-banner:first-child {
    margin: 5px 15px 5px 0px;
}
#banner-9 {
    background-image: url(../images/banners/banner_9.jpg);
}

#banner-10 {
    background-image: url(../images/banners/banner_10.jpg);
}

#banner-8 {
    background-image: url(../images/banners/banner_8.jpg);
}

#banner-7 {
    background-image: url(../images/banners/banner_7.jpg);
}

#banner-6 {
    background-image: url(../images/banners/banner_6.jpg);
}

#banner-5 {
    background-image: url(../images/banners/banner_5.jpg);
}

#banner-2 {
    background-image: url(../images/banners/banner_2.jpg);
}

#banner-3 {
    background-image: url(../images/banners/banner_3.jpg);
}
#banner-11 {
    background-image: url(../images/banners/banner_11.jpg);
}
#banner-15 {
    background-image: url(../images/banners/banner_15.jpg);
}
#banner-16 {
    background-image: url(../images/banners/banner_16.jpg);
}
#banner-17 {
    background-image: url(../images/banners/banner_17.jpg);
}