plone/documentation — pull request #176 by djowett (2014-12-31 12:33:07+00:00)
Title: Correct sample Content Security Policy for Nginx

This eliminates errors like this in my browser (Firefox) console:
Content Security Policy: The page's settings observed the loading of a resource at my.plonesite.com/..../reset.css

The error may have been because "There is also no inheritance from the default source directive."
( as noted at https://scotthelme.co.uk/content-security-policy-an-introduction/#creatingapolicy)

See also: https://www.owasp.org/index.php/Content_Security_Policy_Cheat_Sheet

Same would presumably apply for Apache, but I haven't tested that.