Messages doesn't scroll when add images

Hello there.

I made a chat room. The messages come smoothly with “addMessage” and the page scrolls down.

But if there is a picture in my message, page does not go down. Stop at the beginning of the picture.

How do I fix this problem?

It worked when I specified the height in all the pictures.
It was a little tiring.

style="height:{image height}px"