Hi Ian,
We're looking into this, but I'm afraid there isn't much I can do at the moment as this change is in the core software. It looks like they're interested in moving towards CSS as the HTML values are obsolete.
To note, this doesn't have anything to do with the theme template, but rather the visual editor in your dashboard.
So, my best suggestion is to copy the HTML from the revision where the elements are okay, and to use the text editor for modifying the content in the meantime.