Good day to all.
A week I have been fighting with one question. I can not make the menu, here's how on stackoverflow, so that it is fixed, all elements are horizontally and vertically aligned. 
As I understand it, there should be one common ul with a lot of nested li and dropdown menu,
And now I’ve already seen in YouTube how many different videos and each one does it differently (which is logical), but I don’t understand how to do it more correctly, from the side of future adaptation.
The main question is how to align me completely in the center of the block (height, weight) and how you can make contacts under each other (number and address) in a single ul or li so that they are in the center.
I would be very happy for your help colleagues.