I know you can redesign how the chat box looks in their page, but what i want to do is a bit different. I want the chat box itself to fit 1:1 on the window without any margin on the sides, and don't have the chat headers. is it possible to do that?

It 100% is. Have you tried editing the CSS of the chatbot?

I did, I used the botpress styler to do so. I set the height and width to 100% already, but it did change much So I tried changing the hostUrl to v0 instead of of using v1. It works but everything still in black and white

Have you set the iframe to also be full screen?