.wrapper{
    height: 100%;
    width: 800px;
    display: block;
    margin-left: auto;
    margin-right: auto;
    padding-bottom: 10em;
}
.wrapper iframe{
    width: 800px;
    height: 600px;
    border: none;
}

/* Tablet :768px. */
@media only screen and (min-width: 768px) and (max-width: 991px){
    .wrapper{
        width: 700px;
        padding-bottom: 5em;
    }
    .wrapper iframe{
        width: 700px;
        height: 520px;
    }
}
/* Large Mobile :480px. */

@media only screen and (max-width: 767px) {
    .wrapper{
        width: 400px;    
        padding-bottom: 5em;
    }
    .wrapper iframe{
        width: 400px;
        height: 300px;
    }
}
/* small mobile :320px. */

@media only screen and (max-width: 479px) {
    .wrapper{
        width: 300px; 
        padding-bottom: 5em;
    }
    .wrapper iframe{
        width: 300px;
        height: 200px;
    }
}

.holds-the-iframe {
  background: url(../img/loading.gif) center center no-repeat;
}