Stylus: Can't round-trip various chunks

[DavidSouther]

I grabbed various pieces of "legacy" CSS from around the internet, and had little success round-tripping from CSS through Priest and back through stylus (0.43.7). For testing, I'd recommend grabbing bootstrap.css, a jqueryui theme, and others; run them through priest, pass the output through Stylus. If that works at least mostly sanely, you'll be in good shape.