diff --git a/example-code/document.md b/example-code/document.md
new file mode 100644
index 0000000..d1b246b
--- /dev/null
+++ b/example-code/document.md
@@ -0,0 +1,22 @@
+# Example MarkDown Document
+
+## Heading two
+
+Not much to see here.
+
+Except some ~~deleted text~~ using the [CommonMark](https://commonmark.org/)
+flavour.
+
+## Python code example
+
+This is a simple Python code example:
+```python
+class MyClass:
+    "An uncomplicated class."
+
+    def __init__(self):
+        pass
+```
+
+### Heading three
+That's it.
diff --git a/falconry_pygments_theme/dark.py b/falconry_pygments_theme/dark.py
index 6ee6ed2..84bf802 100644
--- a/falconry_pygments_theme/dark.py
+++ b/falconry_pygments_theme/dark.py
@@ -13,25 +13,25 @@
 # limitations under the License.
 
 from pygments.style import Style
-from pygments.token import (
-    Comment,
-    Error,
-    Generic,
-    Keyword,
-    Name,
-    Number,
-    Operator,
-    String,
-    Token,
-)
+from pygments.token import Comment
+from pygments.token import Error
+from pygments.token import Generic
+from pygments.token import Keyword
+from pygments.token import Name
+from pygments.token import Number
+from pygments.token import Operator
+from pygments.token import String
+from pygments.token import Token
 
-from .common import bold, italic, bold_italic
+from .common import bold
+from .common import bold_italic
+from .common import italic
 
 
 class Colors:
     yellow = '#ffc66d'
-    orange = '#c26230'
-    crimson = '#dc143c'
+    orange = '#df5a1f'
+    crimson = '#ed3b5f'
     brown = '#bc9458'
     green = '#a5c261'
     pear = '#c9cc3f'
diff --git a/falconry_pygments_theme/light.py b/falconry_pygments_theme/light.py
index 6a6dd32..4991e0a 100644
--- a/falconry_pygments_theme/light.py
+++ b/falconry_pygments_theme/light.py
@@ -13,19 +13,19 @@
 # limitations under the License.
 
 from pygments.style import Style
-from pygments.token import (
-    Comment,
-    Error,
-    Generic,
-    Keyword,
-    Name,
-    Number,
-    Operator,
-    String,
-    Token,
-)
+from pygments.token import Comment
+from pygments.token import Error
+from pygments.token import Generic
+from pygments.token import Keyword
+from pygments.token import Name
+from pygments.token import Number
+from pygments.token import Operator
+from pygments.token import String
+from pygments.token import Token
 
-from .common import bold, italic, bold_italic
+from .common import bold
+from .common import bold_italic
+from .common import italic
 
 
 class Colors:
diff --git a/pyproject.toml b/pyproject.toml
index 27102ad..f65e1ff 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -49,3 +49,29 @@ license-files = ["LICENSE"]
 target-version = "py38"
 format.quote-style = "single"
 line-length = 79
+
+[tool.ruff.lint]
+select = [
+  "C9",
+  "E",
+  "F",
+  "W",
+  "I"
+]
+
+[tool.ruff.lint.mccabe]
+max-complexity = 15
+
+[tool.ruff.lint.isort]
+case-sensitive = false
+force-single-line = true
+order-by-type = false
+single-line-exclusions = [
+  "typing",
+]
+force-sort-within-sections = true
+
+[tool.pytest]
+testpaths = [
+    "tests",
+]
diff --git a/tests/test_dark.py b/tests/test_dark.py
new file mode 100644
index 0000000..a19d19d
--- /dev/null
+++ b/tests/test_dark.py
@@ -0,0 +1,13 @@
+import pytest
+
+from falconry_pygments_theme.dark import Colors
+from falconry_pygments_theme.dark import FalconryDarkStyle
+
+_color_names = sorted(name for name in dir(Colors) if not name.startswith('_'))
+
+
+@pytest.mark.parametrize('color_name', _color_names)
+def test_contrast(contrast, color_name):
+    value = getattr(Colors, color_name)
+    if value != FalconryDarkStyle.background_color:
+        assert contrast(value, FalconryDarkStyle.background_color) >= 'AA'
diff --git a/tests/test_light.py b/tests/test_light.py
index 15c08a4..c5fb95b 100644
--- a/tests/test_light.py
+++ b/tests/test_light.py
@@ -1,16 +1,13 @@
 import pytest
 
 from falconry_pygments_theme.light import Colors
+from falconry_pygments_theme.light import FalconryLightStyle
 
-
-_color_names = sorted(
-    name
-    for name in dir(Colors)
-    if not (name.startswith('_') or name == 'light')
-)
+_color_names = sorted(name for name in dir(Colors) if not name.startswith('_'))
 
 
 @pytest.mark.parametrize('color_name', _color_names)
 def test_contrast(contrast, color_name):
     value = getattr(Colors, color_name)
-    assert contrast(value, Colors.light) >= 'AA'
+    if value != FalconryLightStyle.background_color:
+        assert contrast(value, FalconryLightStyle.background_color) >= 'AA'
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..5a37743
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,17 @@
+[tox]
+
+envlist = ruff, py
+
+[testenv]
+deps =
+    pytest
+commands =
+    pytest -v tests/ []
+
+[testenv:ruff]
+deps =
+    ruff
+skip_install = True
+commands =
+    ruff check
+    ruff format --check