Chrome extension for highlighting DOM elements, designed to assist with better debugging of layout issues. Specifically:

• Identifying too-wide overflowing objects.
• Distinguishing block from inline elements.
• Helping to keep track of element alignment.

Adds a distinct colour outline to each visible DOM element, as well as providing a visual prompt for overflowing divs.

display: block; => blue;
display: inline; => purple;
overflowing the viewport => red!

etc..

Get it here: https://chrome.google.com/webstore/detail/element-highlighter/gkamnoiedmidgolhlihkamjpfccohilb