We already track the vertical offset (pageYOffset) so the perimeter is calculated correctly on scroll (and if the component mounts on a page that is already scrolled).

Horizontal scroll is less common, but still it's good idea to support it nonetheless.

Although it's fairly easy to set with the terminal, it gets reset every time you change sensitivity preferences and some people might prefer to not have to manually set it. If you're aiming for this to be an all-in-one mouse fixing tool I think it's probably a good feature to have.

Problem while calibrating. Need to zoom in to the pupil and then track the eye.

You can add a more professional X closer easily by changing the X to × and then changing the stick-to-me.css .stick_close to font-family:Arial,sans-serif; font-size: 17px; font-weight:bold;

while trying to run the app after installing I encountered the following error msg:
[INFO ] [Text ] Provider: sdl2
[CRITICAL] [App ] Unable to get a Window, abort.

Then I went to Kivy installation website: https://kivy.org/docs/installation/installation-windows.html
followed the instructions to install the necessary dependencies for kivy, the dependencies that were missing