1 Pixel Gap Between Drawing Canvasses

I am making a small grid of drawing canvasses. (To test seamless noise)

I have 2 Drawing canvasses each 200 by 200 pixels sitting pixel perfect next to each other in my layout.

When I scale my browser window I see a single pixel column gap flickering between them. Why is this?

I have tried changing the Fullscreen mode and also switching on pixel rounding but I always see the gap at certain resolutions.

How can I fix this?

Thanks