Fix layout in FF; #22

Firefox is more strict than WebKit about the font rules:

> Note: There are few caveats when using the CSS font shorthand. If
> these conditions are not met, the property is invalid and is entirely
> ignored.
>
> [...]
>
> - The order of the values is not completely free: font-style,
>   font-variant and font-weight must be defined, if any, before the
>   font-size value.

https://developer.mozilla.org/en-US/docs/Web/CSS/font