Support dark mode in docs (#1176)

Author: davidbrochart

docs/mkdocs.yml

@@ -172,8 +172,30 @@ plugins:
 theme:
   name: material
   palette:
-    primary: indigo
-    scheme: default
+    # Palette toggle for automatic mode
+    - media: "(prefers-color-scheme)"
+      toggle:
+        icon: material/brightness-auto
+        name: Switch to light mode
+
+    # Palette toggle for light mode
+    - media: "(prefers-color-scheme: light)"
+      scheme: default
+      primary: indigo
+      accent: indigo
+      toggle:
+          icon: material/brightness-7
+          name: Switch to dark mode
+
+    # Palette toggle for dark mode
+    - media: "(prefers-color-scheme: dark)"
+      scheme: slate
+      primary: indigo
+      accent: indigo
+      toggle:
+          icon: material/brightness-4
+          name: Switch to light mode
+
   custom_dir: 'src/overrides'
   favicon: img/favicon.png