I am using a dark themed (Cyborg, to be exact) bootstrap.css file from Bootswatch in my ASP.NET Web Forms application. My plan is to give users the ability to change this theme to be customized upon their login. For example, if user Joe likes the dark theme, he can leave his set to default (dark). However, if Bob likes a light grey theme, he can go into his user settings page and select "light" which would then load the site with a light-colored bootstrap.css theme (like lumen).
So how can I do this? I know this is set in BundleConfig.cs, which is in App_Start and gets registered on Application_Start in Global.asax. Is there a way I can change this on a page load event as well?