The webchat embed isn't designed to take over the full screen. If you need the webchat to be full screen you can follow our guide here: https://botpress.com/docs/cloud/webchat-customization/full-screen-bot/ Also, you may need to add some styles and a

viewport

meta tag to your page to optimize the full screen webchat on mobile, you can check the source code of the "Shareable URL" of your bot (under Integrations > Webchat > Pre-configured) for reference.