TOPIC:

I appreciate the feedback everyone has shared.
I mistakenly thought the the "themes" and "templates" referred to the site itself, not just the learning objects.
Unfortunately, customizing the default website theme and making it responsive (using CSS) is beyond my current abilities, so I will have to pass on using Xerte since the current (non-responsive) theme will not work for my purposes.

Can you explain why you need the authoring workspace to have themes to the point that it means you can’t use Xerte?
As far as responsiveness of the workspace goes - if accessing on lower resolution devices you can close some of the panels to optimise space and you can use the full screen button when populating one of the wysiwyg text boxes. I quite often edit projects on a tablet and low res laptop but if you’re looking for an authoring tool to work on the limited size of a smartphone that’s a very different requirement.
HTH
Ron

What do you mean with default theme in your last message? The default theme of the Learning Objects (both Nottingham and site)? Those are responsive.

If you mean the default look and feel of the workspace, please explain to us what it means for you to be responsive like Ron asked.

To clarify, I do all my site development on my desktop -- and I was not looking for responsive authoring functionality, only for responsive display of the main Xerte web site for the end user (site visitor).

In addition, as I indicated in my original post, the default Nottingham web site settings in my Xerte installation were not responsive, i.e., adjustable for end users on mobile devices:
> Responsive Web DesignResponsive Web Design .

It was this lack of web site responsiveness on mobile devices that prompted my original inquiry. (In addition, please note my original Xerte web site is no longer available to illustrate this display problem since my Xerte installation has already been removed from my server.)