Every day, 30% of specialty and gift e-retailer Fab.com’s sales come from its mobile apps for iPhone, iPad and Android mobile devices, the flash-sale merchant reports. At certain times of the day, mobile commerce accounts for 50% of sales. During two days in the last 30, Fab.com, No. 67 in the Internet Retailer Mobile 400, registered more sales from mobile devices than from PCs, the company says. What’s more, mobile shoppers purchase 20% more items per order than PC shoppers.

Fab.com, which has 10 million registered users and 15,000 products for sale each day, says that success in m-commerce is now a barometer of the company’s success overall. And today it has released an updated version of its mobile app with an eye on making shopping easier for mobile consumers.

The new version of the app features navigation elements that get out of the shopper’s way—as shoppers scroll through products, navigation bars and buttons fade away. Touching a small button atop the screen gets a consumer back to a navigation by category list. Fab.com says it has dramatically improved its search functionality and has added filter by product type and color. And a consumer can sort products by price, best selling, availability and “Most Faved,” which is a listing of products that have been noted as favorites by app users. App users can bookmark favorites and purchases in their Fab profiles.

Fab.com’s formula for building a successful mobile commerce app is build mobile first, keep it simple, and build mobile experiences not mobile shopping, says Fab.com CEO Jason Goldberg.

“For nearly a year now, we’ve been designing and building new features for Fab’s mobile users first, and then taking those features to the web,” Goldberg writes on the company’s blog. “Building mobile first forces us to think about how Fab will be used by people on the go first, and people at their desks second. We’re now in a rapid development cycle on Fab mobile, updating our app with new features and usability improvements every few weeks.”

As for keeping it simple, the merchant’s design philosophy is to get out of the way, Goldberg writes. “We try to make it as simple and easy as possible for our members to discover the Fab products,” he writes. “The functionality of our apps is intended to just fade into the background, not occupy the foreground. It’s not about us. It’s about the products.”

And Goldberg says Fab.com focuses on the mobile experience, not mobile shopping. “Yes, Fab is a retailer,” he writes. “But our entire mobile experience is designed more for browsing and discovery than it is for buying. We want people to want to take their mobile out of their pocket hourly just to see what’s hot on Fab right now. We believe that if people enjoy browsing and discovering on Fab, plenty of sales will happen over time.”