Removed vendor prefixes, except where it fixes a specific bug or quirk
Update archive.php

Revising the "primary" element to use a "div" vs. "section" to bring it into sync with index.php and single.php
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
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
_s: Improve menu toggle accessibility.

Makes it a little easier to use the primary navigation with assistive
devices.

See #545.
Merge pull request #643 from Automattic/aria-toggle

Improve menu toggle accessibility.

Fixes #575.
Merge pull request #580 from jgclarke/patch-1

Use `div`s consistently throughout templates.
_s: Introduce 4.1 archive template tags.

Now uses the new archive template tags and makes archive template
titling way simpler!

Added shims for backwards compatibility, which can be removed once
WordPress 4.3 was released.

See https://core.trac.wordpress.org/changeset/30223
Closes #556.
Check DOING_AUTOSAVE before flushing transients

So that we don’t flush transients more often than necessary.

Fixes #646
Merge pull request #648 from nickdaugherty/check-autosaves

Check DOING_AUTOSAVE before flushing transients.

Fixes #646.
Merge pull request #4 from Automattic/master

Merge from Automattic Master