Removed absolute positioning from GraphView and did minor tweaks to title bar

MaterialGraphProject/Assets/GraphFramework/SerializableGraph/Editor/Drawing/AbstractGraphEditWindow.cs

             m_TitleBarDrawer = new TitleBarDrawer(titleBarData);
 
             m_GraphView.dataSource = source;
-            m_GraphView.StretchToParentSize();
 
             rootVisualContainer.AddChild(m_TitleBarDrawer);
             rootVisualContainer.AddChild(m_GraphView);

MaterialGraphProject/Assets/GraphFramework/SerializableGraph/Editor/Drawing/Styles/TitleBar.uss

 #TitleBar {
     position-type: absolute;
     position-left: 0;
-    position-right: 0;
-    position-top: 0;
+    position-right: -1;
+    position-top: -1;
-    background-color: #333;
+    background-color: #3d3d3d;
+    border-width: 1;
+    border-left: 1;
+    border-right: 1;
+    border-top: 1;
+    border-bottom: 1;
+    border-color: #212121;
 }
 
 #TitleBar #left {