[css-position-3][editorial] Fix whitespace

Author: fantasai

css-position-3/Overview.bs

@@ -981,7 +981,7 @@ The Width of Absolutely-Positioned, Non-Replaced Elements</h3>
 		'left' + 'margin-left' + 'border-left-width' + 'padding-left' + 'width' +
 		'padding-right' + 'border-right-width' + 'margin-right' +
 		'right' = width of containing block
- </code>
+	</code>
 
 	If all three of 'left', 'width', and 'right' are ''left/auto'':
 	First set any ''margin/auto'' values for 'margin-left' and 'margin-right'