Issue with :not() selector followed by other selector

[JohnKis]

Hi there,

First of all thanks for package, it comes really handy if need to minify css on the fly in the browser.

I noticed a minor issue with :not() selectors. If it is followed by another selector, the whitespace between the closing ')' and the next selector will get removed which changes the selector.

Example

Source:

div:not(empty) .main {
   display: block;
}

Result

div:not(empty).main{display:block}

Expected:

div:not(empty) .main{display:block}