Nextcloud doesn´t look right after update from 11.0.3 to 12.0.0 on raspberrypi

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Hi there,
I am running nextcloud on a raspberry pi with actual debian jessie.
after updating nextcloud it doesnt look right in my browser.

Screenshot_20170524_224614.png673×698 35 KB

with 11.0.3 everything looked normal.
any idea or any questions?