diff --git a/demo/World population.Rmd b/demo/World population.Rmd
index f0f803077..e70a0c17d 100644
--- a/demo/World population.Rmd	
+++ b/demo/World population.Rmd	
@@ -2,12 +2,12 @@
 jupyter:
   jupytext:
     cell_markers: region,endregion
-    formats: ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc
+    formats: ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc,.myst.md:myst
     text_representation:
       extension: .Rmd
       format_name: rmarkdown
-      format_version: '1.1'
-      jupytext_version: 1.1.0
+      format_version: '1.2'
+      jupytext_version: 1.11.1
   kernelspec:
     display_name: Python 3
     language: python
diff --git a/demo/World population.ipynb b/demo/World population.ipynb
index a87d30f7f..6487ed8a1 100644
--- a/demo/World population.ipynb	
+++ b/demo/World population.ipynb	
@@ -1435,7 +1435,7 @@
  "metadata": {
   "jupytext": {
    "cell_markers": "region,endregion",
-   "formats": "ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc"
+   "formats": "ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc,.myst.md:myst"
   },
   "kernelspec": {
    "display_name": "Python 3",
diff --git a/demo/World population.lgt.py b/demo/World population.lgt.py
index e485bb043..b6751ea20 100644
--- a/demo/World population.lgt.py	
+++ b/demo/World population.lgt.py	
@@ -2,25 +2,29 @@
 # jupyter:
 #   jupytext:
 #     cell_markers: region,endregion
-#     formats: ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc
+#     formats: ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc,.myst.md:myst
 #     text_representation:
 #       extension: .py
 #       format_name: light
-#       format_version: '1.4'
-#       jupytext_version: 1.1.0
+#       format_version: '1.5'
+#       jupytext_version: 1.11.1
 #   kernelspec:
 #     display_name: Python 3
 #     language: python
 #     name: python3
 # ---
 
-# # A quick insight at world population
-#
-# ## Collecting population data
-#
-# In the below we retrieve population data from the
-# [World Bank](http://www.worldbank.org/)
-# using the [wbdata](https://github.com/OliverSherouse/wbdata) python package
+# region [markdown]
+"""
+# A quick insight at world population
+
+## Collecting population data
+
+In the below we retrieve population data from the
+[World Bank](http://www.worldbank.org/)
+using the [wbdata](https://github.com/OliverSherouse/wbdata) python package
+"""
+# endregion
 
 # region
 import pandas as pd
diff --git a/demo/World population.md b/demo/World population.md
index a11034039..30eb95f18 100644
--- a/demo/World population.md	
+++ b/demo/World population.md	
@@ -2,12 +2,12 @@
 jupyter:
   jupytext:
     cell_markers: region,endregion
-    formats: ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc
+    formats: ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc,.myst.md:myst
     text_representation:
       extension: .md
       format_name: markdown
-      format_version: '1.1'
-      jupytext_version: 1.1.0
+      format_version: '1.3'
+      jupytext_version: 1.11.1
   kernelspec:
     display_name: Python 3
     language: python
diff --git a/demo/World population.myst.md b/demo/World population.myst.md
index 721b8b05e..59b03b05c 100644
--- a/demo/World population.myst.md	
+++ b/demo/World population.myst.md	
@@ -1,11 +1,12 @@
 ---
 jupytext:
+  cell_markers: region,endregion
   formats: ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc,.myst.md:myst
   text_representation:
-    extension: '.md'
+    extension: .md
     format_name: myst
-    format_version: '0.7'
-    jupytext_version: 1.4.0+dev
+    format_version: 0.13
+    jupytext_version: 1.11.1
 kernelspec:
   display_name: Python 3
   language: python
@@ -95,13 +96,6 @@ plt.show()
 
 ## Stacked bar plot with plotly
 
-+++
-
-Stacked area plots (with cumulated values computed depending on
-selected legends) are
-[on their way](https://github.com/plotly/plotly.js/pull/2960) at Plotly. For
-now we just do a stacked bar plot.
-
 ```{code-cell} ipython3
 import plotly.offline as offline
 import plotly.graph_objs as go
@@ -110,10 +104,9 @@ offline.init_notebook_mode()
 ```
 
 ```{code-cell} ipython3
-bars = [go.Bar(x=population.index, y=population[zone], name=zone)
+data = [go.Scatter(x=population.index, y=population[zone], name=zone, stackgroup='World')
         for zone in zones]
-fig = go.Figure(data=bars,
-                layout=go.Layout(title='World population',
-                                 barmode='stack'))
+fig = go.Figure(data=data,
+                layout=go.Layout(title='World population'))
 offline.iplot(fig)
 ```
diff --git a/demo/World population.pandoc.md b/demo/World population.pandoc.md
index 87de7e280..702eec65e 100644
--- a/demo/World population.pandoc.md	
+++ b/demo/World population.pandoc.md	
@@ -1,13 +1,13 @@
 ---
 jupyter:
   jupytext:
-    cell_markers: 'region,endregion'
-    formats: 'ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc'
+    cell_markers: region,endregion
+    formats: "ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc,.myst.md:myst"
     text_representation:
-      extension: '.md'
+      extension: .md
       format_name: pandoc
-      format_version: '2.7.2'
-      jupytext_version: '1.1.0'
+      format_version: 2.11.4
+      jupytext_version: 1.11.1
   kernelspec:
     display_name: Python 3
     language: python
diff --git a/demo/World population.pct.py b/demo/World population.pct.py
index f74c8eee5..bfe3b4b6f 100644
--- a/demo/World population.pct.py	
+++ b/demo/World population.pct.py	
@@ -2,12 +2,12 @@
 # jupyter:
 #   jupytext:
 #     cell_markers: region,endregion
-#     formats: ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc
+#     formats: ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc,.myst.md:myst
 #     text_representation:
 #       extension: .py
 #       format_name: percent
-#       format_version: '1.2'
-#       jupytext_version: 1.1.0
+#       format_version: '1.3'
+#       jupytext_version: 1.11.1
 #   kernelspec:
 #     display_name: Python 3
 #     language: python
@@ -15,13 +15,15 @@
 # ---
 
 # %% [markdown]
-# # A quick insight at world population
-#
-# ## Collecting population data
-#
-# In the below we retrieve population data from the
-# [World Bank](http://www.worldbank.org/)
-# using the [wbdata](https://github.com/OliverSherouse/wbdata) python package
+"""
+# A quick insight at world population
+
+## Collecting population data
+
+In the below we retrieve population data from the
+[World Bank](http://www.worldbank.org/)
+using the [wbdata](https://github.com/OliverSherouse/wbdata) python package
+"""
 
 # %%
 import pandas as pd
diff --git a/demo/World population.spx.py b/demo/World population.spx.py
index 9fe5da91b..c20a321e3 100644
--- a/demo/World population.spx.py	
+++ b/demo/World population.spx.py	
@@ -2,12 +2,12 @@
 # jupyter:
 #   jupytext:
 #     cell_markers: region,endregion
-#     formats: ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc
+#     formats: ipynb,.pct.py:percent,.lgt.py:light,.spx.py:sphinx,md,Rmd,.pandoc.md:pandoc,.myst.md:myst
 #     text_representation:
 #       extension: .py
 #       format_name: sphinx
 #       format_version: '1.1'
-#       jupytext_version: 1.1.0
+#       jupytext_version: 1.11.1
 #   kernelspec:
 #     display_name: Python 3
 #     language: python