How to make such a block comment?

Question

css

How to make such a block comment? Used z-index even does not work!

Answer 1

Why is there a z-index?
https://jsfiddle.net/62zu5yhz/ps
_

Used z-index even does not work!

And in order for it to work, you need to read how it works and in what cases it will not work. Specifically DOM streams

Answer 2

For an avatar, set

position: absolute;
left : // Ваши координаты