Refactor Sass files: remove social media share styles, add author, menu, and media styles

- Removed `social_media_share.scss` and its associated HTML partial for share buttons.
- Added new `author.scss`, `menu.scss`, and `media.scss` files with relevant styles.
- Updated `add.scss` to import new styles and removed obsolete imports.
- Enhanced `comments.scss` with additional styling for smaller text.

.pre-commit-config.yaml

@@ -47,3 +47,8 @@ repos:
             "flake8-implicit-str-concat",
             "pydocstyle>=5.0.0",
           ]
+  - repo: https://github.com/oxipng/oxipng
+    rev: v9.1.4
+    hooks:
+      - id: oxipng
+        args: ["-o", "4", "--alpha"]