Fix z ordering of the overflow tile

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

res/css/views/rooms/_WhoIsTypingTile.scss

@@ -40,6 +40,7 @@ limitations under the License.
 }
 
 .mx_WhoIsTypingTile_remainingAvatarPlaceholder {
+    position: relative;
     display: inline-block;
     color: #acacac;
     background-color: #ddd;