More theme background color appears when opening content item in pop-up: new window

When creating a course resource, such as a page, if you have it set to "Display = In pop-up" in the Appearance settings, when it opens in a new windows, there is no white space. This causes problems if the More theme that is being used has a dark background color for the site. The course name becomes unreadable because the new window takes on the background theme color of the site.

Steps to replicate:
1) Set your site theme to More, and make the background color a dark color.
2) Go to a course, and create a resource such as a Page.
3) In the Appearance Settings of the resource, set the Display option = In pop-up.
NOTE: You must have the Pop-up option enabled for page resources (Site Admin > Plugins > Activity Modules > Page)
4) Click on the resource and you'll see the results in the attachments area.