diff --git a/notebooks/06_data_sources.ipynb b/notebooks/06_data_sources.ipynb
index 9b6de1f..e1fdeb7 100644
--- a/notebooks/06_data_sources.ipynb
+++ b/notebooks/06_data_sources.ipynb
@@ -295,34 +295,33 @@
    "source": [
     "from bokeh.plotting import figure, show\n",
     "from bokeh.models import ColumnDataSource\n",
+    "from bokeh.palettes import HighContrast3\n",
     "\n",
     "# create ColumnDataSource based on DataFrame from the demo data set\n",
     "source = ColumnDataSource(monthly_values_df)\n",
     "\n",
     "# set up the figure\n",
     "p = figure(\n",
-    "    height=300,\n",
     "    x_range=source.data[\"month_name\"],  # use the sequence of strings from the \"month_name\" column as categories\n",
+    "    width=750,\n",
     ")\n",
     "\n",
-    "# create a line renderer with data from the \"freight\" column\n",
-    "p.vbar(\n",
-    "    x=\"month_name\",  # use the sequence of strings from the \"month_name\" column as categories\n",
-    "    top=\"freight\",  # use the sequence of values from the \"freight\" column as values\n",
-    "    width=0.9,\n",
-    "    source=source,\n",
-    ")\n",
+    "# plot values from these columns\n",
+    "columns = [\"freight\", \"passengers\", \"mail\"]\n",
     "\n",
-    "# create a second line renderer with data from a different column\n",
-    "p.vbar(\n",
-    "    x=\"month_name\",  # use the sequence of strings from the \"month_name\" column as categories\n",
-    "    top=\"passengers\",  # use the sequence of values from the \"passengers\" column as values\n",
-    "    # top=\"mail\",       # 🔁 use this line instead of the one above to use data from the \"mail\" column\n",
+    "# use vbar_stack that stacks multiple vbar renderers\n",
+    "p.vbar_stack(\n",
+    "    columns,\n",
+    "    x=\"month_name\",\n",
     "    width=0.9,\n",
-    "    color=\"tomato\",\n",
     "    source=source,\n",
+    "    color=HighContrast3, # use the HighContrast color palette\n",
+    "    legend_label=columns,\n",
     ")\n",
     "\n",
+    "# move legend to left, to avoid overlap with bars\n",
+    "p.legend.location = \"top_left\"\n",
+    "\n",
     "show(p)"
    ]
   },