[totaltec]

So the code you want to add is:

@media (max-width: 1199px) and (min-width: 992px) {
  .navbar-inverse ul#top-main-menu {
    width: auto;
  }
}

You can add it in a couple places, the best one being in your own custom module. If you are comfortable building a custom module that is whaere you should do it. If you are looking for an easier way, you can add this snippet under Look and Feel-> Custom CSS. If you are already using custom CSS (the use custom CSS box is checked) then just add it to the bottom of the file and save. If not, check the box, empty the code that is there if any, and then add your snippet and save.