visionmedia/nib — pull request #156 by feross (2012-12-28 10:29:25+00:00)
Title: Quote -ms-filter value for opacity()

From Microsoft [documentation](http://msdn.microsoft.com/en-us/library/ie/ms530752(v=vs.85\).aspx):

```
When you use -ms-filter, enclose the progid in single quotes (') or
double quotes (")
```

This is because the stuff after -ms-filter has a colon in it, which is non-standard CSS sytnax.