[Bug request] Fix playable window stretching

Related to: On a computer, the tracks are stretched vertically! makes it a different experience between phone and computer. and On computer, the track does not scale proportionally with window size. Additionally, the box with your best lap can cover part of the track.

In responsive mobile view everything works well.
In responsive large view gameCanvas stretches to fit game-screen div. This (for example) makes the car move with different speeds horizontally and vertically.

This is universal between browsers I have tested (Zen, Firefox, Vivaldi), just can be more or less noticable depending on page aspect ratio. For example in Zen vertical cards make the game more noticably stretched but the same result can also be achieved by just stretching the window.