Pretty darn cool! One limitation I wish I could think of a workaround for is that "cutting out" parts of some letters (C, G, J, Q) requires laying a rotated white square over it, with white as the hardcoded background color. So this will only work with other background colors if you know the background color ahead of time or can configure it in JS or something.
Here's a 'C' without the white cut out using a transparent border-right.