omnivore/packages/thumbnail-handler/test/fixtures/findThumbnail.html

<DIV class="page" id="readability-page-1">
    <img src="https://omnivore.work/small.png" alt="small image" />

    <img src="https://omnivore.work/large_and_square.png" alt="large and square image" />

    <img src="https://omnivore.work/wide.png" alt="wide image" />

    <img src="https://omnivore.work/sprite.png" alt="sprite image" />
</DIV>