In my recent developing adventures, my adjacent sibling suggested I try out this Chrome Extension: PerfectPixel
OddsMonkey free trialThis extension lets you overlay an image of your final site over the page rendered in the browser. For example, if you are working in Photoshop, save the whole page as a png/jpg, then use the extension and load the image. You can then pick a reference point and see where you need adjustments. I use Developer Tools (F12) to edit and adjust, then make the changes in my code.
Really cool!