How can I adjust the height of my rasa chat widget?

I want to make sure if this is a mistake due to my misunderstanding of documentation or not.

From Rasa Docs (Your Own Website), I see I can customize my chat widget under Chat Widget -> full documentation, while it redirected to the documentation of Rasa Chat Widget.

I tried to change my HTML to something like this:

While I can see the height of the chat room changed from the demo widget on the same page, I cannot observe the same behavior on my own web page.

Is there anyone who can simulate the same issue? I am wondering if the documentation is out-of-date or if I had made some mistakes while copying the code. Thanks!