I'd like to share with you a few concepts of Responsive Web Design, allowing the content and structure of the website conform to that of the device or browser.
Starting any layout, we typically rely on pixels. Measuring the width of our structure from the design document. Ethan's concept suggests using percentages. Requiring a little more calculation, but otherwise fairly simple.
Now since we do not want to simply shrink everything down, we combine this with the use of CSS Media Queries. These can be thought of as conditional CSS, allowing us to alter the structure as a whole when the browser size drops below a certain size.
Check out this article for a more detailed explanation on media queries: http://css-tricks.com/css-media-queries/
Here is a demo and how to guide that might help: http://filamentgroup.com/lab/responsive_images_experimenting_with_context_aware_image_sizing/
DISCOVERING AN ALTERNATE SOLUTION
After hearing Ethan discuss this concept at Front-End design conference in 2011, fellow WDD instructors and I found ourselves very excited about it. Now most users do not actively resize their browser as they experience the web, but we found that we disliked that the continual re-render as you do. To this end, I've created an alternate solution based off of Ethan's original concept....