How to reproduce:
1. Open the attached project (1325989.zip)
2. Open the Main scene and build for WebGL
3. When the build is finished open the index.html file
4. Uncomment the "config.matchWebGLToCanvasSize = false;" line
5. Host the built files on a web server and connect to it from a browser
6. Try to press the button in the middle of the screen

Expected result: the button is interactable
Actual result: the button can not be pressed or highlighted

Reproducible with: 2020.3.4f1, 2021.1.0a2, 2021.1.4f1, 2021.2.0a14
Not reproducible with: 2021.1.0a1
Could not test with: 2018.4.34f1, 2019.4.24f1 (Missing "script" element in index.html)

Notes:
1. Reproducible on Ubuntu 18.04 and Windows 10
2. When the line is uncommented the vertical mouse cursor's coordinates (displayed on the button) are offset upwards by half of the view's height, making the 0th position be at the center of the view instead of the bottom