What can cause the layout on the iphone to break?

Question

iPhone

Who will tell you why layout can go on an iPhone? In the emulator in chrome, everything is OK, on ​​several android phones (of different sizes) everything is also OK, but on fucking iPhones (5-6 others did not test), the sections do not fit, scroll through the section, and in general sadness and pain.
Here is the site printstudio.ks.ua
Scrolling by sections is done through https://github.com/peachananr/onepage-scroll
Bootstrap 3x framework

In media queries, I set the sizes through vh\vw

Answer 1

You have problems with styles, you need to understand in detail, look at the site in safari, it looks oh how crooked. I'm guessing the problems are due to

.onepage-wrapper .section {
    width: 100%;
    height: 100%;
}
top: 0%, 100%, 200%