Update (2015-05-02): Fixed the icon shrinking, also uploaded my entire stylesheet.

I started using liferea quite a while ago for RSS feed and the only issue I encountered was the way the images were displayed if the image was larger than the window:

By adding the following rule to ~/.config/liferea/liferea.css I got all images resized to fit the window and browsing large photos in the feeds is no longer an issue.

div.content img {
    max-width: 100%;
    height: auto;
}