iframe view mobile safari - keyboard causing wrong height calculation

[dpmango]

#Hello,
I'm facing the issue with native iOS keyboard causing viewport getting smaller with iframe view.

By iframe view I mean visiting the link from skype, instagramm. It work well in regular mobile safari browser. Whole site is 100vh. And I made overlay when keyboard is active 0.5 opacity, so you can see that keyboard is pushing viewport up, instead of going above as overlay.

Because of this bug, every time keyboard is closing, you can see white empty part on keyboard spot for ~ half a second

The link for live testing is https://relonch.surge.sh (if you open in safari it's good. send the link yourself withing some app and you'll what I mean)

I was not even able to google this error, so hopefully you have some ideas why this happens. Thanks

P.S. iOS 10 just in case if it's specific to version..