Hide focus ring for mouse users

Fixes https://github.com/matrix-org/matrix.to/issues/120

src/index.scss

@@ -65,6 +65,11 @@ hr {
     margin: 0 40px;
 }
 
+// Suppress focus ring on form controls for mouse users
+[data-whatintent='mouse'] *:focus {
+    outline: none;
+}
+
 .matrixIdentifier {
     word-break: break-all;
 }

src/index.tsx

@@ -1,11 +1,12 @@
-import React from "react";
-import ReactDOM from "react-dom";
-import "./index.scss";
-import App from "./App";
+import 'what-input';
+import React from 'react';
+import ReactDOM from 'react-dom';
+import './index.scss';
+import App from './App';
 
 ReactDOM.render(
     <React.StrictMode>
         <App />
     </React.StrictMode>,
-    document.getElementById("root")
+    document.getElementById('root')
 );