Shapely Mobile parallax section gap

I’ve designed a front page using parallax sections, and it looks good on screen. But, on my iPhone (in portrait) there are large gaps between sections. On the computer screen these are just 30px, but given the iPhones resolution, the gap must be around 400px?

The picture show a video section, with text section below (which directly beneath on the computer). There’s also large gap above the video to the front (top) page section.

I tried removing the video height instruction thinking that might be it, but no luck?

I think all the gaps between sections are bigger than on the desktop

Hey there

Can i see it? please provide a link to your website and i will check your problem