css3:false might cause gap that shows the prev/next section when scrollingSpeed is low

[alvarotrigo]

Description

When using css3:false sometimes there's a small gap that shows the prev/next section. Specially when using a low scrollingSpeed value.

This can also be seen on the DOM when reaching back section 1. Where top should be 0 and it isn't sometimes:

Link to isolated reproduction with no external CSS / JS

https://codepen.io/alvarotrigo/pen/xxvLbKr

Steps to reproduce it

1. Scroll down
2. Scroll up
3. Check the DOM to see if top is 0 on the fp-wrapper
4. If it is, repeat again until it isn't.

Versions

fullPage.js v4.0.30 and > 4.0.0 probably.