Add dark mode (#554)

src/components/common/apply-dark-mode/apply-dark-mode.tsx

@@ -0,0 +1,20 @@
+import React, { useEffect } from 'react'
+import { useSelector } from 'react-redux'
+import { ApplicationState } from '../../../redux'
+
+export const ApplyDarkMode: React.FC = () => {
+  const darkModeActivated = useSelector((state: ApplicationState) => state.darkMode.darkMode)
+
+  useEffect(() => {
+    if (darkModeActivated) {
+      window.document.body.classList.add('dark')
+    } else {
+      window.document.body.classList.remove('dark')
+    }
+    return () => {
+      window.document.body.classList.remove('dark')
+    }
+  }, [darkModeActivated])
+
+  return null
+}