diff --git a/_config.yml b/_config.yml
index c695d9c..cc6c4f3 100644
--- a/_config.yml
+++ b/_config.yml
@@ -35,12 +35,12 @@ sphinx:
     config:
       html_theme: sphinx_book_theme
       html_theme_options:
-        pygments_dark_style: monokai
+        pygment_dark_style: monokai
       todo_include_todos: true
       intersphinx_mapping:
         py: ["https://docs.python.org/3", null]
         tskit: ["https://tskit.dev/tskit/docs/stable", null]
-        tszip: ["https://tszip.readthedocs.io/en/latest/", null]
+        tszip: ["https://tszip.readthedocs.io/en/stable/", null]
         msprime: ["https://tskit.dev/msprime/docs/stable", null]
         pyslim: ["https://tskit.dev/pyslim/docs/stable", null]
         numpy: ["https://numpy.org/doc/stable/", null]
diff --git a/counting_topologies.md b/counting_topologies.md
index be5bf25..76d1ac9 100644
--- a/counting_topologies.md
+++ b/counting_topologies.md
@@ -51,7 +51,7 @@ def create_notebook_data():
 This tutorial is intended to be a gentle introduction to the combinatorial
 treatment of tree topologies in `tskit`. For a more formal introduction,
 see the {ref}`sec_combinatorics` section of the
-official `tskit` {ref}`documentation<tskit:sec_introduction>`.
+[official `tskit` documentation](tskit:sec_introduction).
 
 The *topology* of a single tree is the term used to describe the branching pattern,
 regardless of the lengths of the branches. For example, both trees below have the
diff --git a/requirements-CI.txt b/requirements-CI.txt
index db1e68c..2915baf 100644
--- a/requirements-CI.txt
+++ b/requirements-CI.txt
@@ -1,16 +1,16 @@
 git+https://github.com/tskit-dev/tsconvert@e99c837e4e26ccbf4f480a4c48626338eeff7dc3
 demes==0.2.3
 demesdraw==0.4.0
-jupyter-book==1.0.2
+jupyter-book==0.15.1
 jupyter-cache==0.6.1
-msprime==1.3.2
-networkx==3.3
-pandas==2.2.2
-pygraphviz==1.13
-scikit-allel==1.3.8
+msprime==1.2.0
+networkx==3.1
+pandas==2.1.1
+pygraphviz==1.10
+scikit-allel==1.3.7
 stdpopsim==0.2.0
 tqdm==4.66.3
-tskit==0.5.8
+tskit==0.5.5
 tskit_arg_visualizer==0.0.1
-tszip==0.2.4
+tszip==0.2.2
 jsonschema==4.18.6 # Pinned due to 4.19 "AttributeError module jsonschema has no attribute _validators"