experiment with more utilities

less/type.less

@@ -133,6 +133,9 @@ mark,
 .bg-danger {
   .bg-variant(@state-danger-bg);
 }
+.bg-gray-dark {
+  .bg-variant(@gray-dark);
+}
 
 
 // Page header

less/utilities.less

@@ -20,6 +20,27 @@
 }
 
 
+// Inverse
+.inverse {
+  color: @gray-lighter;
+  background-color: @gray-dark;
+}
+
+
+// Spacing
+.p-a {
+  padding: @spacer;
+}
+.p-h {
+  padding-left: @spacer;
+  padding-right: @spacer;
+}
+.p-v {
+  padding-top: @spacer;
+  padding-bottom: @spacer;
+}
+
+
 // Toggling content
 // -------------------------