Comment Box Covers Previous Comments When Writing a Reply

The Problem

When writing a reply to a comment, the text box, where you write the reply, keeps getting bigger with each new line.

Eventually, it'll cover all the previous comments, so it's impossible to read them and keep replying.

It starts like this:

And ends up like this:

And it is impossible to make the text box smaller, to access the previous comments.

I think this is a glitch.

The Solution

The intended behavior should be to add a scroll bar to the right, instead of making the text box infinitely bigger with each line of text.