Update css-backgrounds-3/Overview.bs

Co-authored-by: Chris Harrelson <3453258+chrishtr@users.noreply.github.com>

Author: 2 people

css-backgrounds-3/Overview.bs

@@ -2096,7 +2096,7 @@ they apply to the top, right, bottom, and left, respectively.
 
 <p>Portions of the border-image that are rendered outside the border
 box do not trigger scrolling. Also such portions are invisible to mouse
-events and do not capture such events on behalf of the element, but
+events and do not capture such events on behalf of the element,
 but they are included in the [=ink overflow area=] of the element.</p>
 
 <p class=note>Note that, even though they never cause a scrolling