html, body {
    height: 100%; /* Make html and body take the full viewport height */
    width: 100%; /* Make html and body take the full viewport width */
    margin: 0;   /* Remove default body margin */
    padding: 0;  /* Remove default body padding */
    overflow: hidden; /* Hide potential body scrollbars, if only the iframe content should scroll */
}

iframe {
    display: block; /* Iframes are inline by default, change to block for better control */
    width: 100%;    /* Full width of the parent (body) */
    height: 100%;   /* Full height of the parent (body) */
    border: none;   /* Remove the default iframe border */
}