Add TOC nav hover opacity

Removes distraction of full opacity when viewing main page content
Replace CSS slide 100% height with JS

Simplifies CSS hiccups and relies on Javascript for window resizing of
slide to full “screen”
Change slide wrapper tag to avoid styling collision
Clean up layout, re-incorporate nav and footer
Resolve scroll spy menu positioning with updated layout
Deprecate all 100% heights from HTML elements
Clean up and simplify curriculum specialized styles
Add all H3 TOC parsing support

Prevents JS parsing issue from adding ID attribute when non-`slide`
wrapped H3 is encountered.
Favor default layout width over 100%

Aligns visually with header/footer better
Remove unnecessary UL style selector

No longer needed, deprecated and made UL and LI styles appear with
unwanted results.
Merge pull request #201 from github/bring-back-nav-and-pretty-styles

Revise curriculum layout, add improved TOC functionality