    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarsExample10" aria-controls="navbarsExample10" aria-expanded="false" aria-label="Toggle navigation">
          <span class="navbar-toggler-icon"></span>
        </button>

        <div class="collapse navbar-collapse justify-content-md-center" id="navbarsExample10">
          <ul class="navbar-nav">
            <li class="nav-item active">
              <a class="nav-link" href="#">Centered nav only <span class="sr-onl