a img still showing border despite CSS

Hello,

http://leonpaternoster.com/examples/index.php includes two images that link to other pages. Despite my best attempts, a line is still appearing under the images. The relevant HTML is:

And the various link and image styling is:

a:link { text-decoration: none; border-bottom: 1px solid #df7800; color: #df7800; }

a:visited {
text-decoration: none;
border-bottom: 1px solid #3f3f3f;
color: #3f3f3f;
}

a:hover {
text-decoration: none;
border-bottom: 1px solid #333;
color: #333;
}

a img, a img.preview {
border: none;
text-decoration: none;
}

a:link img, a:visited img, a:hover img {
border: none;
text-decoration: none;
}

form, img {
font-size: 100%;
line-height: 1.5em;
}

Any advice would be gratefully received.

Thanks,

Leon