Merge pull request #341 from ascott1/master

fixes #612 make sxs and bookmark expandables addressable by keyboard
skip link now links to the content wrapper
Account for pages without a section
Merge pull request #342 from cmc333333/initial-version

Account for pages without a section
Merge remote-tracking branch 'upstream/master'
hide the scrollbar for windows users when the drawer is closed. hooray
medium priority drawer CSS tasks
shift focus to main content on def close and TOC click
build