Merge pull request #571 from jpyuda/master

definition scope styling tweaks
hide subparts on tablet sized displays
clarify effective dates in drawer
Merge pull request #572 from ascott1/subheader-updates

Hide wayfinding subparts on tablet sized displays
merge upstream
Merge pull request #573 from ascott1/timeline-effective

clarify effective dates in drawer
add what's this links to sidebar help
add 'what's this' link to SxS slide down
build
prevent tables from extending outside of content area
decrease distance of hanging appendix markers
decrease appendix outdents a bit more
use the correct Travis URL
remove comment
Merge pull request #574 from ascott1/sprint18-tweaks

"What's this?" and better tables
decrease font sizes on landing and about page
about page small screen styles
vertically center easy to nav icons
add alt tags
Merge pull request #575 from ascott1/sprint18-tweaks

About page small screens design