Customize the height of the chat widget of Dialogflow messenger integration

I am using Dialogflow's new website integration "Dialogflow messenger". Everything is working fine but when I click on the chat widget the height of the chat window is exceeding the size of the browser window as you can see in the attached snapshot.

I have read out the official [documentation](https://cloud.google.com/dialogflow/docs/integrations/dialogflow-messenger#css-customize) CSS customization of this chat widget but I couldn't found any useful method to handle this issue. I have tried with different browsers like firefox, chrome, safari, etc. But the issue remains the same. The documentation provides only the following CSS variables which don't help out too much.


I will encourage if anyone can provide a solution to this. Thank you