IE fixes and improved navitgation

This pull request does the following:

- Fixes IE8 issue that rendered the back button useless
- Fixes IE8 problems with TOC link styling on click
- Improves the link offsets for the persistent header*


*When links are clicked before the reg is scrolled, the offset of the first section is slightly different. This is a known issue but will not matter once we are loading a single section at a time