I just updated Hummingbird, one of my sites, news.swissinformatics.org, suddenly appeared, on OS X 10.11.6 Safari, with no theme or CSS. This site uses MH Magazine theme. Another site, sisr.news.swissinformatics.org was not affected, it uses an older version of MH Magazine Theme. Other navigators such as Firefox (clean - Private browsing On) and Google Chrome (standard configuration) were not affected. As it was the last change I Disconnected Hummingbird and the site was ok on Safari. Strange, isn't it?
Thanks for caring