Opening comment at bottom of post results in jarring user experience

[cindywu]

To reproduce:

1. add an inline comment in the last line (or last paragraph) of a post.
2. submit a comment with a large character count (a few paragraphs)
3. show the comment you submitted and it will expand height of the window.

The experience should not expand the height of the window. Instead, the window height should not change and we should find a way to display the contents of the inline comment box within the existing height of the window.

[alexkrolick]

One way to solve it - add 1 viewport's worth of overscroll like VSCode or SublimeText. I like to be able to scroll past the bottom of the page so that my eyes stay more in the middle of the screen.