Improve page and archive layouts (#1166)

* Fix collapsed white-space above pagination links

* Improve `page` and `archive` layout
- Center main content on page
- Harmonize sidebar columns to be equal widths

Fixes #1155

* Update CHANGELOG and history

* Position and align right sidebar with the top of the main content

* Offset right sidebar at `$large` viewport

* Add TOC bottom include test post

* Add right sidebar styling edits to documentation site

* Add TOC bottom include test post

docs/_posts/2012-01-03-layout-table-of-contents-post.md

@@ -97,4 +97,4 @@ Make any link standout more when applying the `.btn` class.
 ## Notices
 
 **Watch out!** You can also add notices by appending `{: .notice}` to a paragraph.
-{: .notice}
+{: .notice}