Fix missing offset when opening in-page links
To be ported from HSG Guides:
Resulted from related issue in Guides:
"Content is covered up by menu bar"
https://gitlab.com/HistoryAtState/guides/issues/46
To be ported from HSG Guides:
Resulted from related issue in Guides:
"Content is covered up by menu bar"
https://gitlab.com/HistoryAtState/guides/issues/46