Numbers not displaying

I'm using the [Karla font](http://brick.im/fonts/karla/) with `normalize-opentype.css` on [my blog](http://therubydev.com/) (see the [repository](https://github.com/rafalchmiel/therubydev) for full source code). Here's the problem:


It appears that numerical characters are not displaying but if I turn off `-webkit-font-feature-settings: "kern" 1, "liga" 1, "pnum" 1, "tnum" 0, "onum" 1, "lnum" 0, "dlig" 0;`, the numbers appear (however the type is different and worse than it was with that turned on).