Why the reduction in quality on WebGL?

I have Mini Micro running both on desktop and as WebGL. On desktop (Mac) it looks like this:



But on WebGL, the same content looks like this:



It's a little hard to see with the in-line reduced images above, but the WebGL version is just a bit pixelated.

My Quality settings are the same for all platforms. "Default Canvas Size" in the WebGL player settings is the same as my desktop window size. The image is includes both a sprite (the player character) and a custom tiling system composed of a dynamic mesh (the environment), and the same issue is seen on both.

Is there some simple setting I'm missing that's causing WebGL to come out pixelated?

 

@JoeStrout
This might be related.
Thanks to this post I've found out about and checked your virtual computer, and it looks great! I've worked on an arcade game simulation in my last project, but it has nothing on your Mini Micro.