Working in the browser allows teams to address layout issues across the entire resolution spectrum, design around dynamic data (such as variable character lengths, image sizes, and other dynamic content), demonstrate interaction and animation, gauge performance, factor in ergonomics, and confront technical considerations (such as pixel density, text rendering, scrolling performance, and browser quirks). Static design comps cannot deal with all these considerations, so they should be treated merely as hypotheses rather than set-in-stone specifications. Only when transferred to the browser can any design hypothesis truly be confirmed or rejected.