Our provider hosted sharepoint 365 application is no longer served the theme applied to the sharepoint (app host) site.
We use one of the built-in theme (Orange) - which is correctly applied to the host site and used to work with our app.
We include the CSS with the following tag
<link href='@ViewBag.SPHostUrl/_layouts/15/defaultcss.ashx' type='text/css' rel='stylesheet' />
Where @ViewBag.SPHostUrl is replaced with the App host url.
The resulting URL redirects to (HostUrl)/_layouts/15/16.0.4208.1224/1033/styles/corev15app.css
Which does not contain the css for the Orange theme, instead serves the default blue Office theme.
Whilst the site has been updated recently, the method of retrieving the theme has not - I've not been able to find an explanation, changing the host site Look and Feel has no effect.
Any help would be appreciated!
