How can i get mouse input based on in-game computer screen rather than my whole screen

Im trying to make an in-game computer and i wanted to get movable windows working but its not exactly working as intended. The issue is that whenever i move said window the mouse and the window dont go together. It has something to do with the way i get my mouse input.
2024-12-10 01-16-18.mkv (4.6 MB)