The .css error is normal and expected. That file is an optional theme you can use to change looks, and it does not affect behaviour at all if its not present.

If you do not see status, is most probably because your manager credentials or connection is incorrect, or your button configuration is incorrect. Try this

/usr/local/fop2/fop2_server --test

What do you see? Does it say that it is able to connect to the Asterisk Manager correctly? If not, check your manager credentials in fop2.cfg and be sure that the manager is enabled in /etc/asterisk/manager.conf