Do this if you're using eclipse:

• Open menu Window, menu item Preferences.

• Click tree item General, tree item Editors, tree item Text Editors.

  • Checkbox Insert spaces for tabs: on

  • Textfield Displayed tab width: 4

• Click tree item CSS Files, tree item Editor.

  • Radiobutton Indent using space: on

  • Textfield Indentation size: 4

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With kind regards,
Geoffrey De Smet