Problem with background color when changing Page Template

Totally new to this, making a hopefully simple web site.
And using Modularity Lite template, I selected "Yes! I’d like to enable the optional sidebar" in the Theme Options. Then, within each page I can choose to use that page template as the default and have a sidebar on each page, OR I can choose Full-width, No sidebar. This allows me to have a sidebar/widgets on some pages and not others - the end goal.
But when I choose the Full-width option, the background color I chose in not maintained, and the whole middle of the page is black, which is the automatic footer color. This looks like crap.
Here: side bar in place - proper color background http://vidayoga.org/our-short-story/
here: no side bar - black background http://vidayoga.org/contact/

Can this be fixed? Thanks.