@media only screen and (max-width: 768px) {
  iframe{display:none}
  #iframeLink {
    display: block;
    background: #036;
    width: 85%;
    border: 2px solid #999;
    color: #fff;
    font-weight: bold;
    line-height: 3;
    font-size: 18px;
    font-size: 1.8rem; 
    text-align:center;
  }
}

@media only screen and (max-width: 400px) {
  #iframeLink{line-height:1; padding: 20px 0;}
}