WIP Themes: font size standartization

lib/pages/main/main.page.dart

@@ -539,9 +539,8 @@ class _MainPageState extends State<MainPage> with WidgetsBindingObserver, Ticker
   }
 
   void _showErrorBottomBar(HAError error) {
-    TextStyle textStyle = TextStyle(
-        color: Colors.blue,
-        fontSize: Sizes.nameFontSize
+    TextStyle textStyle = Theme.of(context).textTheme.subhead.copyWith(
+      color: Colors.blue
     );
     _bottomBarColor = Colors.red.shade100;
     List<Widget> actions = [];

lib/pages/widgets/last_updated.dart

@@ -10,8 +10,7 @@ class LastUpdatedWidget extends StatelessWidget {
       child: Text(
         '${entityModel.entityWrapper.entity.lastUpdated}',
         textAlign: TextAlign.left,
-        style: TextStyle(
-            fontSize: Sizes.smallFontSize, color: Colors.black26),
+        style: Theme.of(context).textTheme.caption
       ),
     );
   }