Fix styling links

Author: mwcraig

notebooks/04.Widget_styling/04.00-Layout-and-Styling-Overview.ipynb

@@ -8,10 +8,10 @@
     "\n",
     "This section of the tutorial describes \n",
     "\n",
-    "+ How to [lay out and style Jupyter interactive widgets](06.01-widget-layout-and-styling.ipynb) to build rich and *reactive* widget-based applications.\n",
-    "+ Some [high-level container widgets for laying out widget-based applications](06.14-widget-layout-and-styling.ipynb#Container-Layout-Widgets).\n",
-    "+ Styling available for [some individual widgets](06.13-OPTIONAL-widget-specific-styling.ipynb) (please read this on your own).\n",
-    "+ [Layout and styling of widget labels](06.11-OPTIONAL-widget-label-styling.ipynb) (please read this on your own)."
+    "+ How to [lay out and style Jupyter interactive widgets](04.01-widget-layout-and-styling.ipynb) to build rich and *reactive* widget-based applications.\n",
+    "+ Some [high-level container widgets for laying out widget-based applications](04.01-widget-layout-and-styling.ipynb#Container-Layout-Widgets).\n",
+    "+ Styling available for [some individual widgets](04.05-OPTIONAL-widget-specific-styling.ipynb) (please read this on your own).\n",
+    "+ [Layout and styling of widget labels](04.04-OPTIONAL-widget-label-styling.ipynb) (please read this on your own)."
    ]
   }
  ],