#resImage_300 {
    display:block;
    overflow:hidden;
    background-image:url('https://www.kennelclubcharitabletrust.org/assets/images/3/support-us-keeping-tails-wagging-bb8dd436.jpg');
    background-repeat:no-repeat;
    background-position:center center;
        width:100%;
    background-size: cover;
        height:300px;
}
@media screen and (min-width:700px){
    #resImage_300 {
        background-image:url('https://www.kennelclubcharitabletrust.org/assets/images/9/support-us-keeping-tails-wagging-8abe0ec3.jpg');
                height:440px;
    }
}
@media screen and (min-width:980px){
    #resImage_300 {
        background-image:url('https://www.kennelclubcharitabletrust.org/assets/images/6/support-us-keeping-tails-wagging-e9c08115.jpg');
                height:440px;
    }
}
@media screen and (min-width:1400px){
    #resImage_300 {
        background-image:url('https://www.kennelclubcharitabletrust.org/assets/images/6/support-us-keeping-tails-wagging-e9c08115.jpg');
                height:440px;
    }
}