AdminLTE/build/scss/_header.scss

/*
 * Component: Main Header
 * ----------------------
 */

.main-header {
  padding: 0 16px 0 0;
  .navbar-brand {
    width: $sidebar-width;
    padding: 10px;
  }

  .nav-link {
    padding: 15px 5px;
  }
}

.content-header {
  padding: 15px;
  h1 {
    font-size: 1.8rem;
    margin: 0;

  }
  .breadcrumb {
    margin-bottom: 0;
    padding: 0;
    background: transparent;
    font-size: 1rem;
  }
}