That is strange. Generally I use Google Chrome but yes at times browsers can behave differently. I know I.E does mess up CSS at times for me. But thanks for sharing.
What were you exactly trying to do and what was the issue with Safari?
I hope the page appears as expected in Safari for your viewers.
Merely accessing the WordPress site can be a problem with Safari, in addition to what I mentioned in my post, mostly whenever I attempted to safe an edit in Photo Gallery the page would run and run and never accept it.
Also Firefox v. 46.0.1 only shows a blank page even though my page URL (http://www.kailuaheagroup.com) is displayed in the Firefox URL field.
I have upgraded to Mac OS X 10.11.5 and connected the Mac and cable modem with an ethernet cable instead of the WiFi router I was using, but still get the same results.
Not sure about the Safari thing actually. However it may be worthwhile to see if there are any errors in the console using this tool : https://developer.apple.com/safari/tools/
Firefox I think should show some errors in dev console. Is it in just that one specific version or in all the versions of Firefox?
This issue doesn’t have anything to do with your internet hardware setup If it’s running fine.
Just check the dev console to see if there are any errors?
~Tanveer