diff --git a/.readthedocs.yml b/.readthedocs.yml
index 3ec8ab9..25fc682 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -5,7 +5,4 @@ sphinx:
 
 python:
   install:
-    - method: pip
-      path: .
-      extra_requirements:
-        - docs
+    - requirements: doc/requirements.txt
diff --git a/doc/conf.py b/doc/conf.py
index 9f53bd3..ee3b0d7 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -24,7 +24,7 @@
 # -- Project information -----------------------------------------------------
 
 project = 'streamtracer'
-copyright = '2019, David Stansby'
+copyright = '2019-2021, David Stansby'
 author = 'David Stansby'
 
 # The full version, including alpha/beta/rc tags
@@ -40,6 +40,7 @@
 # ones.
 extensions = ['sphinx_automodapi.automodapi',
               'numpydoc',
+              'jupyter_sphinx',
               ]
 numpydoc_show_class_members = False
 
@@ -57,7 +58,7 @@
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
 #
-html_theme = 'sphinx_rtd_theme'
+html_theme = 'pydata_sphinx_theme'
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
diff --git a/doc/index.rst b/doc/index.rst
index 4ffcbe4..fa501b1 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -5,22 +5,39 @@ streamtracer is a python package for rapid streamline tracing. It is a wrapper
 to compiled fortran code that does the heavy lifting, and is therefore
 relatively fast.
 
-To use, create a :class:`streamtracer.StreamTracer` object::
+To use, create a :class:`streamtracer.StreamTracer` object
+
+.. jupyter-execute::
+
+  import numpy as np
+  from streamtracer import StreamTracer, VectorGrid
 
   nsteps = 10000
   step_size = 0.1
   tracer = StreamTracer(nsteps, step_size)
 
-and a :class:`streamtracer.VectorGrid`::
+and a :class:`streamtracer.VectorGrid`
+
+.. jupyter-execute::
 
   field = np.ones((10, 10, 10, 3))
   grid_spacing = [1, 2, 1]
   grid = VectorGrid(field, grid_spacing)
 
-This can then be used to trace lines through a 3D cartesian vector field::
+This can then be used to trace lines through a 3D cartesian vector field
+
+.. jupyter-execute::
 
   seeds = np.array([[0, 0, 0], [0, 0, 1]])
-  streamlines = StreamTracer.trace(seeds, grid)
+  tracer.trace(seeds, grid)
+
+and the traced field lines can be accessed via. the ``.xs`` attribute
+
+.. jupyter-execute::
+
+  print(f'Number of traced lines: {len(tracer.xs)}')
+  line_lengths = [len(x) for x in tracer.xs]
+  print(f'Line lengths: {line_lengths}')
 
 For more information see the :mod:`streamtracer` API docs.
 
@@ -52,6 +69,10 @@ Code reference
 Changelog
 =========
 
+1.1.2
+-----
+Fixed the example code listed above.
+
 1.1.1
 -----
 Fixed wheel building to use the oldest supported version of numpy for each
diff --git a/doc/requirements.txt b/doc/requirements.txt
new file mode 100644
index 0000000..8bcf348
--- /dev/null
+++ b/doc/requirements.txt
@@ -0,0 +1,7 @@
+jupyter-sphinx
+numpydoc
+pydata-sphinx-theme
+sphinx
+sphinx-automodapi
+sphinx_rtd_theme
+streamtracer
diff --git a/setup.cfg b/setup.cfg
index aa8e8b5..eb4a48c 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -21,7 +21,9 @@ tests =
   pytest
   pytest-cov
 docs =
+  jupyter-sphinx
   numpydoc
+  pydata-sphinx-theme
   sphinx
   sphinx-automodapi
   sphinx_rtd_theme
diff --git a/streamtracer/streamline.py b/streamtracer/streamline.py
index d79bcf2..18d5f0e 100755
--- a/streamtracer/streamline.py
+++ b/streamtracer/streamline.py
@@ -144,6 +144,7 @@ class StreamTracer:
     def __init__(self, max_steps, step_size):
         self.max_steps = max_steps
         self.ds = step_size
+        self.xs = None
 
     @property
     def max_steps(self):