Some combination of authored styles causing "cover" image to disappear #103

This happens in both scroll and paginated modes in Thorium. I am filing in ReadiumCSS to see if this affects other reading systems.

EPUB contains HachetteEpubV1.3.css with:

.sectionpp {
    left: 0;
    top: 0;
    height: 100%;
    width: 100%;
    overflow: hidden;
    text-align: center;
    position: absolute;
}

and XHTML markup:

<section xmlns="http://www.w3.org/1999/xhtml" class="sectionpp" xmlns:epub="http://www.idpf.org/2007/ops" epub:type="cover" role="doc-cover"><a id="cover" tabindex="-1"><img alt="" class="imgpp" src="cover/cover.jpg" /></a>
</section>

If I remove position: absolute;, or height: 100%;, the image is displayed normally. Otherwise, invisible (the image CSS box itself is fine, it is the containing div that causes issues)