docs(dev-manual): css RTL/LTR guidelines

developer_manual/html_css_design/css.rst

@@ -263,3 +263,46 @@ There are some predefined classes for public use to ease developing an applicati
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 | ``.inlineblock``                             | Make an element an inline block                                                                                                                |
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+RTL guidelines
+==============
+
+Dos and Don'ts
+--------------
+
+.. list-table::
+   :header-rows: 1
+
+   * - Bad
+     - Good
+     - Description
+   * - Use physical properties ``margin-left``
+     - Use logical properties ``margin-inline-start``
+     - Using logical properties automatically adapts to LTR/RTL
+   * - Use ``left`` or ``right`` 
+     - Use inset-inline-start/end
+     - Keep positioning direction-aware 
+   * - Use text-align: left/right
+     - Use text-align: start/end
+     - Text aligns correctly in both modes
+   * - Use border-left/right
+     - Use border-inline-start/end
+     - Borders flip correctly
+   * - Use float: left/right
+     - Use float: inline-start/end
+     - Float respects direction
+   * - Assume RTL “just works”
+     - Test your app with RTL languages 
+     - Using the correct css value is not always enough to avoid bugs
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