.ad_wrapper {
  clear: both;
}
.ad_wrapper #ad_468x60 {
  margin: 25px auto 10px;
  width: 468px;
  height: 60px;
}
@media screen and (max-width: 467px) {
  .ad_wrapper #ad_468x60 {
    float: none;
    clear: none;
    z-index: 100;
    bottom: 0;
    left: 0;
    position: fixed;
    margin: 0 auto;
    height: 50px;
    width: 100% !important;
    text-align: center;
    background-color: #ccc;
  }
}