.c-banner { display: block; height: 535px; width: 800px; background-size: contain; background-repeat: no-repeat; border: #efefef 2px solid; background-position: center center; margin: 0 auto; }

/* for responsive ads */
@media screen and (max-width: 559px) {
    .c-banner { height: 174px; width: 260px; }
    .ad a.c-banner { height: 174px; width: 260px; }
}
@media screen and (min-width: 560px) and (max-width: 767px) {
    .c-banner { height: 280px; width: 420px; }
    .ad a.c-banner { height: 280px; width: 420px; }
}
@media screen and (min-width: 768px) and (max-width: 1024px) {
    .c-banner { height: 400px; width: 600px; }
    .ad a.c-banner { height: 400px; width: 600px; }
}