Dcat-Admin/resources/assets/dcat/sass/components/_horizontal-menu.scss

.horizontal-menu {
  .content-wrapper, .main-footer, .main-header {
    margin-left: 0!important;
  }

  .header-navbar {
    position: -webkit-sticky;
    position: sticky;
    top: 0;
  }

  .header-navbar.navbar-horizontal, .main-sidebar {
    top: 68px;
    position: fixed;
    width: 100%;
    //z-index: 99!important;
    height: inherit;
    min-height: auto;
    bottom: inherit;
  }

 .header-navbar .main-menu-content {
   padding-left: 1.5rem!important;
   padding-right: 1.3rem!important;
   transition: .3s ease all;
   background: inherit;
   margin-left: 0;
 }

  .wrapper .sidebar {
    height: inherit!important;
  }

  .nav.nav-pills {
    margin-bottom: .8rem;
  }
}

@media (min-width: 576px) {
  .navbar-expand-sm {
    -webkit-flex-flow: row nowrap;
    -ms-flex-flow: row nowrap;
    flex-flow: row nowrap;
    -webkit-box-pack: start;
    -webkit-justify-content: flex-start;
    -ms-flex-pack: start;
    justify-content: flex-start;
  }
  .navbar-expand-sm, .navbar-expand-sm .navbar-nav {
    -webkit-box-orient: horizontal;
    -webkit-box-direction: normal;
  }
}