The first thing that comes to mind is this: whatever you do to make the perfect site, you face the same elephant in the same room as the rest of us, which is that unless your viewers all have calibrated screens, you can’t win.
My iPhone gives me one version, the iPad another, and the only thing that still looks true is what I see using my desktop computer, the same device on which I make the transmitted files. Of course, I might be fooling myself too, thinking that what I see on it today is what I saw months ago. How can I possibly know?