arc-hive-wordpress-theme/dist/assets/scss/modules/_navigation.scss

@include breakpoint(small){
  .menu {
    list-style:none;
    .menu-item-has-children {
      .sub-menu {
        display:none;
      }
      &:hover {
        .sub-menu {
          display:inline-block;
        }
      }
    }
  }
}
@include breakpoint(medium){
}
@include breakpoint(large){
}