[css-nav-1] Fix the wrong description

Fix the wrong description about selecting the candidate which doesn't overlap with search origin before measuring the distance.

Author: jihyerish

css-nav-1/Overview.bs

@@ -1187,7 +1187,7 @@ run the following steps:
             unless it too is overlapped with another higher item, recursively.
     * Else
         1. Set <var>candidates</var> be the subset of its items which satisfies one of the following conditions:
-            * the item overlaps with <var>searchOrigin</var> and its <a>boundary box</a>'s
+            * the item doesn't overlap with <var>searchOrigin</var> and its <a>boundary box</a>'s
                 * top edge is below the bottom edge of <var>searchOrigin</var>'s <a>boundary box</a> if <var>dir</var> is {{SpatialNavigationDirection/down}}
                 * bottom edge is above the top edge of <var>searchOrigin</var>'s <a>boundary box</a> if <var>dir</var> is {{SpatialNavigationDirection/up}}
                 * right edge is left of the left edge of <var>searchOrigin</var>'s <a>boundary box</a> if <var>dir</var> is {{SpatialNavigationDirection/left}}