_s Starter Theme
Resources

Fluid images are the foundation of responsive design but they can be a little tricky in WordPress. The starter theme _s, freely available on GitHub, tackles fluid images with grace and aplomb.
Quick Overview
Browsers give inconsistent results when you’re working with images that have hardcoded widths in WordPress. In _s, the Automattic Theme Team carefully selected all possible images that your WordPress theme needs to handle in three declaration blocks. There’s standard fluid image CSS for all images, and auto height
for images that get added to the WordPress media library. What about the treachery of IE8? Well, _s has a patch for really large WordPress images in IE8, already built in.