Updated CSS rules

docs/technology/frontend/css.md

@@ -12,12 +12,14 @@
         1. Styling CSS with Prettier SHOULD NOT use any custom options ([Prettier's philosophy on options](https://prettier.io/docs/en/option-philosophy))
     1. CSS MUST be linted with [Stylelint](#stylelint)
         1. Stylelint MUST use the `stylelint-selector-bem-pattern` plugin
+        1. Stylelint COULD use the `stylelint-order` plugin
+        1. Stylelint COULD extend the [TNA Frontend stylelint configuration](https://github.com/nationalarchives/tna-frontend/blob/main/stylelint.config.js)
         1. Stylelint COULD be configured to ignore some rules
 1. **Style content**
     1. CSS colours MUST be defined as either hex values or `rgb`
     1. CSS colours defined using `rgb` SHOULD use the newer syntax (`rgb(255 128 0)` rather than `rgb(255, 128, 0)`)
-    1. CSS colours with alpha MUST use the newer `rgb` syntax (e.g. `rgb(255 128 0/0.5)`)
-    1. CSS MUST work without support for [CSS variables](https://developer.mozilla.org/en-US/docs/Web/CSS/Using_CSS_custom_properties)
+    1. CSS colours with alpha SHOULD use the newer `rgb` syntax (e.g. `rgb(255 128 0/0.5)`)
+    1. CSS SHOULD work without support for [CSS variables](https://developer.mozilla.org/en-US/docs/Web/CSS/Using_CSS_custom_properties)
     1. CSS variables COULD be used to enhance customisability
 1. **Media**
     1. If we expect the web content to be printed or saved to a PDF, CSS print styles SHOULD be considered

mkdocs.yml

@@ -17,15 +17,12 @@ nav:
       - Technical Governance Board: organisation/technical-governance-board.md
   - Technology:
     - technology/index.md
-    - Frontend:
-      - HTML: technology/frontend/html.md
-      - JavaScript: technology/frontend/javascript.md
-      - CSS: technology/frontend/css.md
-    - Backend:
-      - Python: technology/backend/python.md
-      - Scala: technology/backend/scala.md
-    - Database:
-      - Postgres: technology/database/postgres.md
+    - HTML: technology/frontend/html.md
+    - JavaScript: technology/frontend/javascript.md
+    - CSS: technology/frontend/css.md
+    - Python: technology/backend/python.md
+    # - Scala: technology/backend/scala.md
+    - Postgres: technology/database/postgres.md
     - Infrastructure:
       - Amazon Web Services (AWS): technology/infrastructure/aws.md
       - Containers: technology/infrastructure/containers.md