What about:
Michael Nengerman

My article include guide to how to vertically center using position absolute, top 50% and margin: (half the size of element).

The only thing that I forgot to mention is that, If you don’t know the height of element, you can use transform: translateY(-50%).

But for those who read my previous article, they may already know that and for this article I’ll update it, So that if someone who haven’t read my previous article reads it then he/she learn how to do that without knowing the height of element. (Thanks for letting me know!)