Fix: removed byte order mark (BOM) from CSS which was causing browsers t...

I noticed the ```table.sortable span.sign``` rule was being ignored in my application and tracked it down to a BOM / ZERO WIDTH NO-BREAK SPACE character at the beginning of the CSS. I don't know if this was partly to do with the minification/concatenation tool I'm using, but, I figured it was safe/recommended to remove regardless.