I found the solution on a previous post, I needed to add this code

@media screen and (max-width: 992px){
#masthead {
display: block !important;
}
.site-branding {
width : 100%;
}
#main-slider {
margin-top: 154px;
}
.main-navigation.left-menu,
.main-navigation.right-menu {
display: none;
}
}