Update css-overflow-4/Overview.bs

Co-authored-by: Tab Atkins Jr. <jackalmage@gmail.com>

Author: flackr

css-overflow-4/Overview.bs

@@ -2191,7 +2191,7 @@ showing in which case space is reserved for the <a>scrollbar gutter</a>.
 	This is the JavaScript equivalent of the <{button/scrolltarget}> HTML attribute.
 
 	A 'button' with a non-null {{HTMLButtonElement/scrollTargetElement}}
-	represents a <dfn export>scroll marker control</dfn> that forms a <dfn>scroll marker group<dfn> for its nearest [=scroll container=]
+	represents a <dfn export>scroll marker control</dfn> that forms a <dfn>scroll marker group</dfn> for its nearest [=scroll container=]
 	in which exactly one control in the group can have its 'checked' state set to true.
 	A [=scroll marker control=] with a true 'checked' state can be styled by the '':checked'' pseudo-class.