I'm starting my initiative for improved commenting UI. The goal is to drive more first and second comments in the majority of threads. While I have a long list of improvements in the pipeline, the first wave is pretty simple.

I reduced the size of the comment box at the top level from 150px to 100px. The size of a textbox often inadvertently conveys the expected size of text to submit, whether the person who created the page or the person who uses the page realizes it. By making it smaller, it invites more casual first comments.

The second-level text boxes, replying to a comment, are still the same size at 150px.

While I was at it a few other improvements came with it. One is I added an 'Expand' button to make the text box bigger. I previously picked a size I thought was comfortable for both short comments and long comments, but it wasn't ideal for either. So now it's faster to adjust it, especially on mobile.

The submit button is now separated from the others, so you don't have to scan the now larger selection of buttons to find it. That chips away another tiny fraction of friction. The boxes also do a better job of scrolling into view.

This is wave 1 and likely the lightest wave.