Remove unused transition-delay mixin
Remove unused user-select mixin
Coding conventions
Remove unused old-ie mixin (use @if -ie instead)
Rename rounded-corners mixin
Border-radius mixin update

- Remove fallback for Firefox < 4
- Support older versions of WebKit when specifying value in % units
Merge branch 'master' of github.com:guardian/frontend into mixin-refactor
Merge pull request #3921 from guardian/mixin-refactor

Mixins refactor