How can I resize my chat pop up window for IOS devices?

[Tjw85]

I’ve been made aware that the chat function pop up on my site is too large so when open you cannot scroll or exit. Apparently this is an issue with IOS devices. 

Upon chatting with John at Shopify support he also suggested my screen size is too large and that my theme developers should look into reducing it as this might be a contributing factor. 

[hyuk10]

I have the same issue with my shop, apparently this happens for all iOS devices and whatever theme is in use or any third party app for live chat. It would be helpful if we can manually fix or set up the size of the live chat. I tried to look into the code but there was no change on mobile. The changes only applied for desktop when changing the live chat size window.