After installed and enable theme, I got the message on every page except pages of administration:
The website encountered an unexpected error. Please try again later.
And in Drupal log messages I got:
LogicException: You are not allowed to use css in #attached in drupal_process_attached() (line 661 of /var/www/***/core/includes/common.inc).
Drupal version: 8.0.0-beta15
Closed: cannot reproduce
Code
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