Different resolutions and monitor sizes, different browsers with their own unique quirks, smartphones and tablet brands with variable operating systems. What all of it means, aside from lots of testing, is that something can't just be done once any more. It seems like any design work produced needs to be redone in a bunch of different ways. Even if you set something up to be responsive to the device it's meant for, it still involves extra work and having to be able to visualize what your design will look like in a bunch of different ways.
Just picture what it would have involved doing all of the extra designs and resizing back in the glory days of advertising before computers. But then I guess that's the catch...all of these new mediums for marketing are digital based. What a clever web these machines have weaved.
