diff --git a/site/docs/src/common/install-stack.md b/site/docs/src/common/install-stack.md
new file mode 100644
index 00000000..09b001cc
--- /dev/null
+++ b/site/docs/src/common/install-stack.md
@@ -0,0 +1 @@
+See the official `stack` installation [documentation](https://docs.haskellstack.org/en/stable/install_and_upgrade/).
diff --git a/site/docs/src/installation.md b/site/docs/src/installation.md
index 27f59229..9cbdcfcb 100644
--- a/site/docs/src/installation.md
+++ b/site/docs/src/installation.md
@@ -1,15 +1,27 @@
 # Installation
 
+## Environment requirements
+
+- OS: `Ubuntu 22.04` or `macOS 12`.
+- `stack` is installable.
+- `normalizer` is installable.
+
+## Install `stack`
+
+{{#include ./common/install-stack.md}}
+
+## Install `normalizer`
+
 Install the `normalizer` executable globally via [stack](https://docs.haskellstack.org/en/stable).
 Then, the `normalizer` executable will be available on `PATH`.
 
-## Install from the repository
+### Install `normalizer` from the repository
 
 {{#include ./common/enter-repository.md}}
 
 {{#include ./common/install.md}}
 
-## Install from Hackage
+### Install `normalizer` from Hackage
 
 ```sh
 stack update
@@ -17,11 +29,11 @@ export LC_ALL=C.UTF-8
 stack install --resolver lts-22.16 eo-phi-normalizer
 ```
 
-## Update
+## Update `normalizer`
 
 Run `stack install ...` as in one of the methods above.
 
-## Uninstall
+## Uninstall `normalizer`
 
 Learn where `stack` installs programs.
 
diff --git a/site/docs/src/pipeline.md b/site/docs/src/pipeline.md
index e8b066c0..d1215a36 100644
--- a/site/docs/src/pipeline.md
+++ b/site/docs/src/pipeline.md
@@ -1,5 +1,9 @@
 # Pipeline
 
+## Install `stack`
+
+{{#include ./common/install-stack.md}}
+
 ## Enter the repository
 
 {{ #include ./common/enter-repository.md }}