div.o_iframe {
    text-align: center;
}

iframe {
    width: 100%;
    height: 1200px;
    /*background: url('data:image/svg+xml;charset=utf-8,<svg xmlns="http://www.w3.org/2000/svg" width="100%" height="100%" viewBox="0 0 100% 100%"><text x="50%" y="50%" font-size="42" text-anchor="middle">Loading...</text></svg>') 0px 0px no-repeat;*/
}