Style tweaks and minor code clean-up for title bar

MaterialGraphProject/Assets/GraphFramework/SerializableGraph/Editor/Drawing/DrawData/TitleBarDrawData.cs

 		public void Initialize(IGraphAsset graphAsset)
 		{
 			if (graphAsset == null)
-				return;
-			
-			title = graphAsset.GetScriptableObject().name;
+				title = "";
+			else
+				title = graphAsset.GetScriptableObject().name;
 		}
     }
 }

MaterialGraphProject/Assets/GraphFramework/SerializableGraph/Editor/Drawing/Drawer/TitleBarDrawer.cs

             };
             AddChild(rightContainer);
 
-            m_title = new Label(new GUIContent("testttt"))
+            m_title = new Label(new GUIContent(""))
+				pickingMode = PickingMode.Ignore
             };
             leftContainer.AddChild(m_title);
 

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

     align-items: stretch;
     background-color: #212121;
     padding-bottom: 1;
-    padding-left: 1;
+    margin-left: 1;
 }
 
 #TitleBar #left,
 }
 
 #TitleBar #left {
-    /* background-color: #f00; */
-#TitleBar #left #title {
+#TitleBar #title {
-    font-size: 12;
+    font-style: bold;
 }