Extra margin on mobile

Site URL: https://www.studiokotoisa.fi

I have extra margin on mobile view (see the grey are on the right) and I think it's because there's something wrong with my testimonial slider. I had similar problem before but I can't remember how it was fixed.

Try adding this to Design > Custom CSS

/* fix right margin */
@media screen and (max-width:767p) {
html, body {
	overflow-x: hidden;
}
}

I updated your max-width value and then it worked, thanks!