Fix audio 'scroll to element' for horizontal

Source/Resources/Bridge.js

@@ -235,6 +235,18 @@ function goToEl(el) {
     if(elBottom > bottom || elTop < top) {
         document.body.scrollTop = el.offsetTop - 20
     }
+
+    /* Set scroll left in case horz scroll is activated.
+
+        The following works because el.offsetTop accounts for each page turned
+        as if the document was scrolling vertical. We then divide by the window
+        height to figure out what page the element should appear on and set scroll left
+        to scroll to that page.
+    */
+    if( document.body.scrollTop == 0 ){
+        var elLeft = document.body.clientWidth * Math.floor(el.offsetTop / window.innerHeight);
+        document.body.scrollLeft = elLeft;
+    }
 
     return el;
 }