mobile menu default is expanded status

I'm having the same problem...
The problem probably located in "css/custom-media.css" ?

I'm also trying to figure out how to change this so that it starts collapsed rather than expanded. Any clues?

For other folks, I fixed this by adding the following to custom-style.css:

@media (max-width: 766px) {
.region-primary-menu {
display:none;
}
}