Jun 4, 2013 · 2 minutes

Many publishers have already made up their minds about the “mobile Web.” They’ve simply decided it’s the same as the “normal Web” and have accordingly built their sites with responsive design, so they can automatically adapt to the size of the screen on which they are being viewed. PandoDaily takes that approach, as does Vox Media’s Polygon, and Mashable, to name a few. One site, one solution for all screens. The Huffington Post is swinging both ways, using responsive design while offering native mobile apps too.

But while publishers are charging ahead into a world of flexi-HTML5, an important part of their product is lagging behind: the stuff that brings in the cash.

The advertising industry has so far struggled to keep pace with the needs of a responsive Web world. An early stop-gap solution has involved simply switching in ad units of varying sizes depending on where they’re viewed. A firm called ResponsiveAds offers banners and square units that adapt dynamically as the page changes sides, but it so far notable for its lack of company.

New York-based Undertone, meanwhile, has moved early with its bet on the mobile Web by building an HTML5 platform for “brand-focused” responsive units. That means the platform, called Screenshift, moves beyond the banner to provide what Undertone calls a “high impact experience” in responsive design. One of its first executions in the format was done for L’Oreal (here’s an example), a drop-down unit that takes over much of your screen – you know, the ads brands love and consumers hate.

Undertone co-founder Eric Franchi says the ad industry is just at the beginning of the responsive era. It has taken this long for brands to catch up not so much because of a lack of demand – although marketers are certainly still learning the ropes – but because not even the most sophisticated digital ad companies are pushing them in this direction. “The solutions don’t exist,” says Franchi. “There hasn’t been a reason for them to develop responsive ads.”

Undertone believes that the mobile Web is the future for publishers, so advertisers have to follow. “We ultimately think that all of our customers want to run across screens, because all consumers want to run across screens,” says Franchi.

It’s unlikely that Undertone and ResponsiveAds will hold the first-mover advantage for long. Google is said to be working on responsive ad units, too. The search and advertising giant told Digiday that it’s testing a number of possible solutions to the challenge.

Once Google is in the market, you can expect that responsive ads will fast become an industry standard.

[Illustration by Hallie Bateman]