Dark mode.

hooks/useTheme.js

@@ -0,0 +1,21 @@
+import { useDispatch, useSelector } from 'react-redux';
+import { setTheme } from 'redux/actions/app';
+import { getItem, setItem } from 'lib/web';
+import { THEME_CONFIG } from 'lib/constants';
+import { useEffect } from 'react';
+
+export default function useLocale() {
+  const theme = useSelector(state => state.app.theme || getItem(THEME_CONFIG) || 'light');
+  const dispatch = useDispatch();
+
+  function saveTheme(value) {
+    setItem(THEME_CONFIG, value);
+    dispatch(setTheme(value));
+  }
+
+  useEffect(() => {
+    document.body.setAttribute('data-theme', theme);
+  }, [theme]);
+
+  return [theme, saveTheme];
+}