One of the more persistent challenges we’ve faced at my day job in recent years has been adapting our “plug-in” web apps to the design constraints of our resellers’ website products. Think, for example, of a camera store widget that can be added to an existing page on an existing website. The user should be able to select from a library of different designs and color schemes to try to make the integration with the site as seamless as possible. When we first built the infrastructure for handling different internal designs, we also came up with some baseline widths (500px, 750px, 950px, etc) that we thought would be able to accommodate the needs of any website designer. Then we wrote separate CSS style sheets for each design, color, and width combination. This seemed like a reasonable approach at the time, but in practice it’s become a real headache as we’re constantly having to adapt to the specific width requirements of each new vendor. And our recent forays into WordPress themes and Facebook frames have only exacerbated the issue.