Here’s a tip for catching unsized images during development. Add this CSS rule somewhere in your stylesheet:

img:not([width]):not([height]) {
  border: 2px solid red !important;
}
Then any images without width and height attributes will be drawn with a red border so they’re easy to spot.

Found via 37signals

http://37signals.com/svn/posts/2979-css-tip-spot-unsized-images-during-development

Spot unsized images during development

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