Mobile keyboard covers text field in modal

Hello, I’m prototyping a webiste style for a client’s developer in Webflow who is going to build a chat on a full screen modal for mobile.

The problem is that the mobile keyboard completely covers the text input field, here are images of the modal:

How can I make it work as in Whatsapp where the text field “floats” or remains above the keyboard.

Here is a sample page, in mobile click on the chat tab at the bottom of the screen:
http://criol.webflow.io/queja

Thanks in advance!

Ok, I’m so silly, I solved it with fixed positioning.