Fix strange carousel width on http://gohugo.io/

The solution is to add `table-layout:fixed` when `display:table` is used
as per the answer given at:

    http://stackoverflow.com/questions/21230184/owl-carousel-inside-a-table-cell-parent-makes-parent-to-expand-weird

Fixes #1465

docs/static/css/HPstyles.css

@@ -167,6 +167,7 @@ a:hover {
 .callout {
     color: #ffffff;
     display: table;
+    table-layout: fixed;
     height: 420px;
     width: 100%;
     background-color: rgb(118,156,172);