I created a web page by using html CSS and JavaScript. In the home page, I added a pop up contact button and form, it is working but pop up window is opened at the top of page. Home page is like one page you scroll. I added the button to the footer but form is opened close to header. I want to it to open while user see the end of the page. I hope I can clear the problem.

https://github.com/ipeksaygut/website in this link there are HTML- CSS-JS files of only home page.

I am really beginner, I really do not understand the problem. T

If something is needed let me know to share to clear problem! Window is seen as the picture but I want to see it at the end of page. I added photo of window how it is seen and where I want to see it.