Unfortunately, I am still seeing the problem with Safari in my web site under development and on your demo web site. I’m running Adventurous Pro 2.1 theme. The problem is not consistent. If I reset our Safari browser and clear out the cache, the header starts working again. If I spend time on the web site, the problem returns. I tried this on four different Macs. Two Macs are running OS X 10.9.4 and the other two are running OS X 10.9.5. All are running Safari 7.0.6.
Here is another video of what I am seeing. When I reset the Safari browser the first time, the problem happened right away after clicking on the first web site link. When I reset the Safari browser the second time, the problem appeared after navigating through the web site for 2 minutes. It is a bit random.
https://www.dropbox.com/s/dhuzcnpwle3nb77/problem-still.mp4