I wonder, should we perhaps be a lot more forgiving about the `link` tag. 
E.g. `<link href="foo.css">` will be missed, right? because it doesn't have the `rel="stylesheet"` thing. 
How about something like this:
```python
for element in CSSSelector('style,link')(page):
    if element.tag == 'link':
        # check that it's used for css
        if not (element.attrib.get('rel') == 'stylesheet' or element.attrib.get('type') == 'text/css' or element.attrib.get('href').lower().endswith('.css')):
           # let's not go there then
           continue
```

More forgiving makes more people happy.