Horizontal scrolling on mobile website issue

It looks like the problem is to do with your header logo on mobile. Do you have any code targeting it? I would recommend making the mobile height around 60px rather than 97px.

This CSS could also help:

@media only screen and (max-width: 768px) {
  .header .header-title--use-mobile-logo .header-mobile-logo img {
    max-width: 100%;
  }
}