The GetAsCSS function has been around since FileMaker Version 7, and I have to admit to never having used it before a few days ago. I recently integrated CloudMail (from 360Works) into a FileMaker project, and for version 1 my client was planning text only emails. Jesse Barnum noted in his instructional video that basic html could be quickly achieved use the GetAsCSS function, so I did some experimenting. Sure enough, font size, font color, bolding, and italics show up using GetAsCSS.
Douglas Alder recently posted an article on using the GetAsCSS function in web viewers, and did quite a bit of experimenting to figure out the limitations:
This idea has been documented before, (Using a Web Viewer as a Field) but I rediscovered it myself recently and thought I might have something to add. As was pointed out in The Support Group article, sometimes as a developer, you want to display a long chunk of text (anything that requires scrolling within a field) to the user, but not allow them to edit that text. Some examples might include displaying a block of help text, or a long software agreement. It is obviously possible to format your text using HTML to achieve this effect, but that can become complicated especially if you are not that good at HTML. Fortunately FileMaker offers a much simpler way to display formatted text this using the GetAsCSS function.
You'll need to read his post for all the details. There are some position issues that don't apply as much to emails, so until my client is ready to use HTML formatted emails, we are going the GetAsCSS route.
Totally Unrelated Cool Note: Douglas Alder's son released a new app called GifTV for the Apple TV.