Optimised CSS

Used http://www.codebeautifier.com to optimise CSS. Sorted selectors and properties.
Messages from optimiser:
```
4
    Optimised font-weight: Changed "bold" to "700"
17
    Invalid property in CSS2.1: background-size
29
    Optimised font-weight: Changed "bold" to "700"
44
    Optimised font-weight: Changed "bold" to "700"
```