flex-direction: column;
      display: flex;
    }
    toolbar {
      flex: 0 0 auto;
      border-bottom: 1px solid black;
      display: flex;
    }
    result-area {
      flex: 1 1 auto;
      display: block;
      min-height: 0;
      overflow-y: auto;
    }
    </style>

    <toolbar id="toolbar"></toolbar>
    <result-area id="result_area"></result-area>
  </template>

.btn:active, .btn-group > .btn.active,\n.btn-group-vertical > .btn:focus,\n.btn-group-vertical > .btn:active,\n.btn-group-vertical > .btn.active {\n  z-index: 1;\n}\n\n.btn-toolbar {\n  display: -ms-flexbox;\n  display: flex;\n  -ms-flex-wrap: wrap;\n  flex-wrap: wrap;\n  -ms-flex-pack: start;\n  justify-content: flex-start;\n}\n\n.btn-toolbar .input-group {\n  width: auto;\n}\n\n.btn-group > .btn:not(:first-child),\n.btn-group > .btn-group:not(:first-child) {\n  margin-left: -1px;\n}\n\n.btn-group > .bt...