That's correct, I used Signage Studio Desktop version. Since posting, I dug through the code of the widget which is here:
newbielink:http://www.tripadvisor.com/WidgetEmbed-selfserveprop?amp;writereviewlink=false&popIdx=false&linkt=2&iswide=true&rating=true&uniq=437&lang=en_US&nreviews=0&locationId=182017 [nonactive]
In my html document I added an explicit link to the CSS that is referenced in the widget code above. The widget displayed properly.
Unfortunately, this work around won't be suitable for production. If TripAdvisor updates the structure of the HTML or the CSS, my scene may break.
To me, it appears that the HTML component is not loading or applying the CSS properly.
Thanks again.
Bruce.