Webview loading animation doesn't work

[inclement]

Due to a missing static/style.css in the webview bootstrap source, the webview loading page probably doesn't show any animation by default. The code it assumes to be present is included in the test app, at https://github.com/kivy/python-for-android/blob/master/testapps/testapp_flask/static/style.css .

Further, it would be even better to make the loading page somehow customisable.

[KeyWeeUsr]

Perhaps we could use some template for the loading screen with a default .css unless specified otherwise e.g. via console argument or .spec property?