Before anything else, this is a great project; always excited with Smalltalk -> JS projects. I noticed some blurriness as well, I wonder if it's an issue with Retina displays? I uploaded a screenshot here if it's helpful: http://imgur.com/a/NxhQp

Yes, on retina plain SqueakJS uses half the resolution, and by default the canvas interpolates. It looks sharper if you force pixel doubling: https://squeak.js.org/run/#url=https://freudenbergs.de/bert/... (by appending the pixelated flag to the url) but this looks worse when scaled, e.g. on iPad, so it's not the default. Caffeine, however, does support an HTML canvas - just try the included example which opens a workspace in HTML.