The use of certain standard elements facilitates usability regardless of the browser or device someone uses to access your site. Usability.gov -- in Guideline 4.1: Design for Common Browsers -- suggests that designers should attempt to accommodate ninety-five percent of all users. Meanwhile, Guideline 4.2: Account for Browser Differences cautions designers to watch out for the following: Do not assume that all users will have the same browser features, and will have set the same defaults. It gets complicated. And when ecommerce is involved, with its critical security issues, it gets really complicated. But it's not impossible to design something that works extraordinarily well for the vast majority of users.
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