ayout {
        position: absolute;
        top: 100px;
        right: 100px;
        bottom: 100px;
        left: 100px;
        height: calc(100% - 200px);
        background-color: #eee;
        overflow: hidden;
        box-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
      }

      app-header {
        background-color: #4285f4;
        color: #fff;
      }

      paper-icon-button {
        --paper-icon-button-ink-color: white;
      }

    </style>
  </custom-style>

</head>
<body>

  <!-- app-header-layout 