If it’s working in FF and not in IE, then it sounds like whatever you’re doing isn’t supported by IE – are you expecting RH to do something about that?
I've used the same CSS outside RH, attached to a HTML page, and it works in IE. It's only when the CSS is used in RH that it stops working. It looks like RH is preventing it from working somehow.
If it was something in RH that wasn’t calling/using that css design, then you’d expect it to fail in FF also. Have you examined the HTML code of a topic that should be using it to see if it’s being used? Have you tried the “Apply to All” setting in the RH SSL recipe as a test?
RH has the habit of sometimes removing CSS that it doesn't understand.
While the CSS will work fine in your output (if the browser supports
it), having that markup in your topic CSS may trigger a RoboHelp CSS
Personally, I always have a different CSS which is copied to the output
You may want to report this behaviour to Adobe as a bug:
The CSS isn't in the topc itself, it's in the main CSS file. I've tried it both ways and I've copied the CSS into my output manually after I've generated it, but it's still the same. Weirdly, the buttons look fine when I preview them in RH and when I use the "View with..." button to preview in the browser itself.
On which browser? IE? In that case, the browser rendering mode can
ignore certain CSS styles if they don't fit the browser's mode. (Such as
CSS3 for IE8 mode.)