Ive noticed that on Moodle 2.6 a sitewide theme overrides either a category, or course level theme on a mobile device - specifically on an iPhone or iPad.
I have themeA set as my sitewide theme.
I have then set ThemeB at a course level.
On a desktop themeB shows properly, rescales as expected for a boostrap theme and seeminly works fine.
When tested on a mobile device however, ThemeA is displayed.
I have reset theme cache, purged all site caches, double tested and through safari's develop menu proven that ThemeA is being forced on my iphone.