Hi there,
i didn't add any custom css to popups...
I tested as android build on my phone (Samsung S3 GT-I9300, Android 4.3.0 ), in android broswer (Version 4.3) on phone and in chrome browser (39.0.2171.93) on phone. Chorme works fine, only in android browser and as android build i see these white fields.
I've enabled the "share with support" toggle.
To reproduce:
Open app
Select "Erholung Erleben"
Move forward in footer to the next pages, here the popups will open
Do you need more Info to have a look at the issue?
Cheers