Salesforce Trailhead

Since upgrading to Safari 12, when working with Salesforce Trailhead and the Playground orgs, nothing seems to be rendering properly. Tabs are coming up with content out of the context of other UI elements, I am getting messages about needing permission to open new tabs, new tabs are coming up entirely blank, and when working with SF communities, themes are not being displayed which is keeping me from editing pages in communities.

When working in Chrome, everything behaves as expected. I have been through the new preference settings in Safari to try to determine what may have been added that would be causing this but have not been able to pick up anything. Is there anyone more familiar with the inner workings of Safari 12 that might be able to advise which switch to flip to get things working again. Thanks in advance.