Hi @demisjohn and thanks for joining the forum.
It looks like you put that rule in the style sheet of the containing page. That won’t affect anything inside the iframe. It’s a property of iframes: as far as styles and JS go, the containing page and the contained page are as separate from each other as if they were different browser windows.
I updated the web integration guide to make this more clear. I also added a couple of paragraphs on how to use the css query parameter, which I think had been missing here. And I coded examples of how to use it in this jsfiddle.
Makes sense?