Actually, there might be some hope. All of my utilities use a javascript library called fabric.js to handle the HTML canvas element(s). I did a bit of searching and it turns out it has a bug that causes the issue you're seeing when being used with a retina display (which a lot of newer Macs have):
https://github.com/kangax/fabric.js/issues/2744
I snagged a version of fabric.js that is supposed to fix the issue and have set up a temporary version here:
OOTP Park Generator - Retina Test
Klew, can you check that out and see if it works properly?