Question about offset calculation

[FrankMerema]

Hi,

First of all great library! It's saving me a lot of work :D

I a question regarding scrolling within a <section> which is a scrollable container. (overflow: auto)
In this section I have some content which needs to have a sticky header which stays within the boundings of its scrollable parent.

On Chrome and FF this is working perfectly because of the css position: sticky, IE is not working as expected and thats why I came here.

But I noticed some weird behavior if the position fixed is used (on IE or in chrome by using the prop useFixed: true).

My questions are:
Q1: On line 240 I see you are subtracting the offset from the start, in my case it made the it.stickyStart a minus number. So I removed the subtraction and everything worked fine. So can we remove this subtraction or do I miss an important case? (tests are passing if I remove this subtraction)

Q2: On line 333 I see you are using the stickyBitOffset passed into the props (or 0 if none provided), but this is also miscalculating the offset if you are using it inside a scrollable section. My suggestions would be to use the it.offset which is calculated at line 239. This offset is consisting of the scrollElOffset plus the offset passed in via the props.

Maybe this is related to #327.

Thanks in advance!

[FrankMerema]

I have made a branch in my fork but it is based on my typescript branch, which I also needed for testing in my Angular application.