TORONTO—Responsive web design seems like a time saver because you design your site once and it adapts to all devices — desktop, laptop, tablet and smartphone. Sounds great, but it's not that simple, said speaker Stacey Mulcahy at FITC Toronto on April 24.

"The tenets of responsive design sound easy, but it's actually quite hard to test everything on all those devices," said Mulcahy, senior developer at Brooklyn, NY-based digital agency Big Spaceship. Her talk was titled "The Responsible Response to Responsive Design."

There are other issues to be resolved as well. "Content is definitely coming back as king," she said. The more successful responsive websites are those like Boston Globe, which are primarily focused on content. It's when you add an interactive level that things get complicated. Users expect the interactive experience to run exactly the same on all screen sizes and resolutions, Mulcahy said. "Responsive design takes care of the layout, but not the experience." Designers still have to think about how and why users access their sites on different devices.

And there is the issue of banner ads. Advertisers on media sites pay for a certain location on the desktop/laptop page, but what happens to that position when the layout adapts to a smartphone screen?

Mulcahy had these recommendations for those designers and developers venturing into responsive design:

1. Adopt a mobile first approach. "Go back and evaluate your content. What is the essence of the user experience?" Decide what content is necessary on a smartphone versus a laptop. And remember sometimes better engagement happens with a fast page, rather than a full page.

2. Developers should set up their grid beforehand and then give the grid to designers to do their thing.

3. Remember there is no standard fold anymore — it changes depending on the device and orientation of the device.

4. Add lots of time for QA. Mulcahy recommends Adobe Shadow, a new inspection and preview tool that allows device pairing, synchronous browsing and remote inspection. In short it allows you to test your design simultaneously on many devices, both Android and iOS.