.hdr {
    text-align: right;
    width: calc(100vw - 20px);
    max-width: 800px;
}

.iframe-container {
    position: relative;
    overflow: hidden;
    width: calc(100vw - 20px);
    max-width: 800px;
    padding-top: 500px;
    /* Adjust this percentage for the ideal aspect ratio of your sheet (height/width * 100) */
}

.iframe-container iframe {
    position: absolute;
    overflow: hidden;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}