Use element.getBoundingClientRect().top rather than element.offsetTop

[lukeify]

Line 99:

sectionOffsets[sections[i].id] = sections[i].offsetTop;

offsetTop fetches the element relative to the top of the nearest relatively positioned element, not relative to the document. If you by chance have a relatively-positioned element in between your navbar and your sections, this causes the scrollto functionality to scroll to the incorrect location.

This can be fixed by using getBoundingClientRect().top (or .y) instead:

sectionOffsets[sections[i].id] = sections[i].getBoundingClientRect().top;

Perhaps add a setting for DOM-absolute or relative offsets also, if you consider this a breaking change (I don't think it should be, but I can't test all use cases).

Would you be able to fix this (alternatively I can make a PR) and push a new release to packagist? Thanks!

[lukeify]

Any progress on this? @jbutko