Moves modal close button to left. (#55)

veggieseasons/lib/screens/details.dart

@@ -82,8 +82,8 @@ class DetailsScreen extends StatelessWidget {
             ),
           ),
           Positioned(
-            top: 0.0,
+            top: 16.0,
-            right: 16.0,
+            left: 16.0,
             child: SafeArea(
               child: CloseButton(() {
                 Navigator.of(context).pop();

veggieseasons/lib/widgets/close_button.dart

@@ -8,7 +8,7 @@ import 'package:flutter/cupertino.dart';
 import 'package:flutter/widgets.dart';
 import 'package:veggieseasons/styles.dart';
 
-/// Partially overlays and then blurs its child.
+/// Partially overlays and then blurs its child's background.
 class FrostedBox extends StatelessWidget {
   const FrostedBox({
     this.child,