Integrate HTML/CSS/JS Site to Grav CMS

I have a simple site that uses HTML/CSS/JS and I want to add it to my grav site as well. Ive seen examples of people inserting the raw html code in between grav code.

But for some reason I dont understand why its not functioning as intended. Can anybody help me in making this work?

Ive attached the link for the zip files containing the grav project and the html project.
https://drive.google.com/file/d/1PbduScEWSF5HLHh5RAsi70sgbFaN84pp/view?usp=sharing

Thank you!

You cannot copy & paste any HTML code with different CSS styles and maybe external JS dependencies into Grav. It's OK for code fragments, but in most cases it won't work for complex documents.

A better approach is to integrate an external page in an iFrame. You can use either a simple iFrame or a responsive iFrame solution. E.g. https://marketmix.com/de/grav-cms-responsive-iframes/

Translation here:
https://translate.google.com/translate?hl=en&sl=auto&tl=en&u=https%3A%2F%2Fmarketmix.com%2Fde%2Fgrav-cms-responsive-iframes%2F

-- Harald