feat: main screen use flex layouy

ui/lib/main.dart

@@ -67,10 +67,13 @@ class MyApp extends StatelessWidget {
               body: Center(
                   // Center is a layout widget. It takes a single child and positions it
                   // in the middle of the parent.
-                  child: Row(children: <Widget>[
+                  child: Flex(direction: Axis.horizontal, children: <Widget>[
-                const NavDrawer(),
+                const Flexible(
+                  flex: 1,
+                  child: NavDrawer(),
+                ),
                 const VerticalDivider(thickness: 1, width: 1),
-                Expanded(child: child)
+                Flexible(flex: 7, child: child)
               ]))),
         );
       },

ui/lib/navdrawer.dart

@@ -20,9 +20,7 @@ class _NavDrawerState extends State<NavDrawer> {
 
   @override
   Widget build(BuildContext context) {
-    return ConstrainedBox(
+    return Row(
-        constraints: const BoxConstraints(maxWidth: 220),
-        child: Row(
             mainAxisAlignment: MainAxisAlignment.start,
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
@@ -68,14 +66,10 @@ class _NavDrawerState extends State<NavDrawer> {
                     icon: Icon(Icons.settings),
                     label: Text('设置'),
                   ),
-                  NavigationRailDestination(
-                    icon: Icon(Icons.computer),
-                    label: Text('系统'),
-                  ),
                 ],
                 //groupAlignment: -1,
                 minWidth: 56,
               ))
-            ]));
+            ]);
   }
 }