Update layout CSS for mobile devices

[DKudleichuk]

Description

The current script does not calculate the viewport height correctly on Phones.
Please update following

https://github.com/alvarotrigo/fullPage.js/blob/master/src/css/fullpage.css#L247-L249

from

body:not(.fp-responsive) .fp-overflow{
    max-height: 100vh;
}

to

body:not(.fp-responsive) .fp-overflow{
    max-height: 100vh;
    max-height: 100dvh; /* fix for new browsers */
}

[alvarotrigo]

Can you provide some isolated reproduction where we can reproduce the issue?
Notice your concern is only on sections using scrollOverflow.

• Where are you having issues? Android? iOS?
• What browsers are you having issues with? Chrome? Safari? Firefox?

This example looks ok to me on iOS:
https://github.com/alvarotrigo/fullPage.js/blob/master/src/js/resize.js#L219