resize to mobile phone

Hello,

I managed to resize my home page to mobile phone screen size but I don't know how to do the same for the other pages.

For example each photo is linked to a new page if you click on them.

https://helenhebert.com/new-page-1

so I'd like to resize all those pages.

Can someone help with this?

Thanks a lot 

Add to Design > Custom CSS

@media screen and (max-width:767px) {
.gallery-fullscreen-slideshow {
    height: 35vh !Important;
}
}