This question already has an answer here:
So the new top bar is rolling out across SE. Well, kinda; SO's top bar is still completely fundamentally different, with a different color, the icons in slightly different places, and so forth.
But the difference that annoys me the most is that the SE top-bar is not sticky. The SO top bar is sticky by default; the SE one doesn't even have an option to be sticky.
The whole point of expanding the top-bar to other SE sites is to make the sites all consistent with one another. But for those of us who use SO primarily, there's no consistency. On one site, we have instant access to our "inbox", network sites, and so forth. On every other site, you have to scroll up to the top of the page to see that.
Could we make the SE top bar at least be able to share the same position as the SO top bar? It doesn't have to be the default, but having the option for consistency would be nice.