Removed vendor prefixes, except where it fixes a specific bug or quirk
Inherit box-sizing for best practice

Using inheritance allows easy override on other elements, and also it’s the best practice.
Remove border-radius mixin
Better WordPress Coding standards.

This minor commit kicks off code improvements to _s so that it’s fully in line with WordPress Coding Standards rules.
Better build config for Travis CI. [skip ci]
Better rules for Travis CI.
The commit https://github.com/WordPress-Coding-Standards/WordPress-Coding-Standards/commit/6986e21182def2111135e46493484581ac494632#diff-9dbd3b63f5d2589b5eb1701e92893803 began (in part) breaking Travis CI builds in _s. There’s most certainly room for improvement to _s code with regard to WordPress Coding Standards, but let’s exclude WordPress.Variables.GlobalVariables and correct all coding standards errors on localhost before removing the excludes from our GitHub-hosted ruleset.
Closing DIV comment for site-branding

Call it OCD, but I feel like we need a closing DIV comment for  ```site-branding``` :)
_s: Merge branch 'pr/561'.
_s: Remove remaining box-sizing prefix.

Also removes the box-sizing mixin, as it is of no use anymore.

See http://caniuse.com/#feat=css3-boxsizing
See #558.

Fixes #561.
_s: Merge branch 'pr/616'.
Merge pull request #640 from emiluzelac/patch-34

Closing DIV comment for site-branding.
_s: Merge branch 'pr/609'.

Props @mor10 for documentation.
Fixes #641.
Merge branch 'master' of https://github.com/Automattic/_s