[css-2017] Remove redundant text

Closes #2210

Author: frivoal

css-2017/Overview.bs

@@ -141,7 +141,7 @@ Background: The W3C Process and CSS</h3>
 		<dt><a href="https://www.w3.org/TR/css-syntax-3/">CSS Syntax Level 3</a>
 		  [[!CSS-SYNTAX-3]]
 		<dd>
-			Replaces CSS2&sect;4.1, CSS2&sect;4.1, CSS2&sect;4.2, CSS2&sect;4.4, and CSS2&sect;G,
+			Replaces CSS2&sect;4.1, CSS2&sect;4.2, CSS2&sect;4.4, and CSS2&sect;G,
 			defining how CSS is parsed.
 
 		<dt><a href="https://www.w3.org/TR/css-style-attr/">CSS Style Attributes</a>