Fixed sizes have to do the way the web traditionally works. You have to keep in mind that "responsive" is a somewhat new concept. The web is about 20 years old and we've only seen responsive layouts in the past 2-3 years. That said, it would be great to have a built-in mechanism to detect the maximum width supported and display a banner that fits that space. For example, today we can setup a campaign with, say, two banner sizes, 728x90 and 300x250, at the same time. Revive will display the 728x90 banner when this campaign is assigned to a 728x90 zone, and will display the 300x250 banner when this campaign is assigned to a 300x250 zone. One step further would be the Revive tag to detect the width, and this particular zone would display (for example) the 728x90 banner when the resolution is high enough and the 300x250 banner at lower resolutions. Currently, there are a few known workarounds to that. You can define zones without a width and height (it is possible, just enter * x *), in this case, both banners (728x90 and 300x250) will be displayed at the zone. Then you can set up banner limitation to display the 300x250 for mobile browsers and the 728x90 banner for non-mobile browsers. I hope I have helped.