.iframe-wrapper {
    position: relative;
    width: 100%;
    padding-bottom: 75%;
    height: 1500px;
    overflow: hidden;
}

.iframe-wrapper iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: 1px solid #ddd;
}

/* For mobile devices */
@media (max-width: 768px) {
    .iframe-wrapper {
        padding-bottom: 120%;
    }
}