In Safari 8.0.7, if user scrolls down and then back up to top of viewport, the header will slideup. Maybe something that says "If at top of viewport (give or take 200px) always show navigation"?
Within the blog area, the header has no background which means the links aren't legible on the white background.
Enhancement: Easier access to main navigation.
I have included two solution options.
I think option one works better.