Fixes #5729: Nested striped tables

* Scopes striping to immediate children of the tbody and tr
* For nested tables, sets a background color of @bodyBackground, to override the default transparent bg

less/tables.less

@@ -48,6 +48,11 @@ table {
   tbody + tbody {
     border-top: 2px solid @tableBorder;
   }
+
+  // Nesting
+  .table {
+    background-color: @bodyBackground;
+  }
 }
 
 
@@ -143,8 +148,8 @@ table {
 // Default zebra-stripe styles (alternating gray and transparent backgrounds)
 .table-striped {
   tbody {
-    tr:nth-child(odd) td,
-    tr:nth-child(odd) th {
+    > tr:nth-child(odd) > td,
+    > tr:nth-child(odd) > th {
       background-color: @tableBackgroundAccent;
     }
   }