Thanks for the rapid response! I do appreciate it ...
Using the <center> approach doesn't work. Before I contacted you I had partial success by putting the [booking nummonths=3] shortcode in a table construct as follows :
<div align="center">[booking nummonths=3]</div>
Oddly, this causes the calendars to be properly centered, but the calendar legend and the response form remain locked to the left-hand margin. This makes me think that maybe there's some CSS or other code in your plugin that's overriding WordPress itself and forcing those elements to the left margin (at least that's what happens in the FireFox 14 rendering of the page).
The page URL is
Thanks in advance ...