Javascript to shift window for in-page anchors.

In my research about issues with in-page anchors, I found this code that
might be useful.  More details once I've adapted it.

js/tex4ht-footnote-hack.js

@@ -25,3 +25,23 @@ $( ".footnote-mark" ).tooltip({
         }
     }});
 });
+// The following code was borrowed from:
+// https://github.com/pierre-rouanet/sphinxjp.themes.basicstrap/commit/05ac6055be8cbb6097f16ab106df5244c19a067f
+// which was licensed under the MIT license.
+
+$(window).load(function () {
+    /*
+     * Scroll the window to avoid the topnav bar
+     * https://github.com/twitter/bootstrap/issues/1768
+     */
+    if ($(".navbar.navbar-fixed-top").length > 0) {
+        // var navHeight = $(".navbar").height(),
+        var navHeight = 40,
+            shiftWindow = function() { scrollBy(0, -navHeight - 10); };
+
+        if (location.hash) {
+            setTimeout(shiftWindow, 1);
+        }
+        window.addEventListener("hashchange", shiftWindow);
+    }
+});