#fixed-block {
    position: fixed;
    right: 2em;
    top: 100px;
    background: wheat;
    padding: 1.5em 1.5em 1.5em 3em;
    width: 15em;
}

* html { background: fixed url('about:blank'); }

* html #fixed-block {
    position: absolute;
    top: expression(eval(document.documentElement.scrollTop) + 100 + 'px');
}