How to align Sprite to canvas coordinates

Hi everyone.
I was trying to align Sprite object to screen coordinates but it seems not right.


You can see my canvas is not same size with window (renderer.domElement.width != window.innerWidth and (renderer.domElement.height!= window.innerHeight ) so that when i try this example then my result is different.
https://threejs.org/examples/webgl_sprites.html
So may you help me a solution to find corner point inside canvas (not full window) ?
Thank u.