Corrected carousel arrows to active.#6494, #6489

Corrected the carousel arrows to active on resizing the browser window.

docs/examples/carousel.html

@@ -88,6 +88,7 @@
       text-shadow: 0 1px 1px rgba(0,0,0,.4);
       background-color: transparent;
       border: 0;
+      z-index: 10;
     }
 
     .carousel .item {