add stub to express lack of mobile functionality

package.json

@@ -22,6 +22,7 @@
     "object-hash": "^1.3.0",
     "ramda": "^0.26.1",
     "react": "^16.6.3",
+    "react-device-detect": "^1.6.2",
     "react-dom": "^16.6.3",
     "react-image": "^1.5.1",
     "react-portal": "^4.2.0",

src/components/Dashboard.jsx

@@ -18,6 +18,8 @@ import DefaultCover from './presentational/covers/Default'
 
 import { parseDate } from '../js/utilities'
 
+import { isMobile } from 'react-device-detect'
+
 class Dashboard extends React.Component {
   constructor (props) {
     super(props)
@@ -95,6 +97,24 @@ class Dashboard extends React.Component {
   render () {
     const { actions, app, domain, ui } = this.props
 
+    if (isMobile || window.innerWidth < 1000) {
+      return (
+        <div>
+          {process.env.features.USE_COVER && (
+            <StaticPage showing={app.flags.isCover}>
+              {/* enable USE_COVER in config.js features, and customise your header */}
+              {/* pass 'actions.toggleCover' as a prop to your custom header */}
+              <DefaultCover showAppHandler={() => {
+                /* eslint-disable no-undef */
+                alert('This platform is not suitable for mobile. Please re-visit the site on a device with a larger screen.')
+                /* eslint-enable no-undef */
+              }} />
+            </StaticPage>
+          )}
+        </div>
+      )
+    }
+
     return (
       <div>
         <Toolbar

yarn.lock

@@ -5549,6 +5549,11 @@ rc@^1.0.1, rc@^1.1.6, rc@^1.2.7:
     minimist "^1.2.0"
     strip-json-comments "~2.0.1"
 
+react-device-detect@^1.6.2:
+  version "1.6.2"
+  resolved "https://registry.yarnpkg.com/react-device-detect/-/react-device-detect-1.6.2.tgz#2587e4d1dc15bdfce7a1bf5417624ecd2a2fc31f"
+  integrity sha512-XIBgwIfpGAknm7tXe/YNbx4ieIR7IyFI3KNfSQk4UjHVy97UHe/nB7iJj8R/dDsI+I/ZzPR4HJ39Gh5tI4nhxw==
+
 react-dom@^16.6.3:
   version "16.6.3"
   resolved "https://registry.yarnpkg.com/react-dom/-/react-dom-16.6.3.tgz#8fa7ba6883c85211b8da2d0efeffc9d3825cccc0"