Is there a way to get a theme working in a mashup? I know this feature is not fully supported. I installed the highvis theme and was able to get it to work using the path in Qlik UI, but I don't know how I can pass the theme I want in my mashup...
It will allow you to control your webpage around the charts, but not customize the colors of the charts, for example.
The real workaround is to edit the require.js file (located at C:\Program Files\Qlik\Sense\Client\assets\external\requirejs on the server). You will see at the end a string containing all the theme related stuff. You will probably find the same file somewhere in the desktop version.
But note that this will affect all of your charts for all the applications on the server. Also note that it will be overwritten once you update Qlik.