Add styling for checked grid rows, per oruga/butterball

tailbone/templates/grids/complete.mako

@@ -44,6 +44,9 @@
        :data="visibleData"
        :loading="loading"
        :row-class="getRowClass"
+       % if request.use_oruga:
+           tr-checked-class="is-checked"
+       % endif
 
        % if request.rattail_config.getbool('tailbone', 'sticky_headers'):
        sticky-header

tailbone/templates/themes/butterball/base.mako

@@ -242,6 +242,31 @@
         white-space: nowrap;
     }
 
+    /**************************************************
+     * grid rows which are "checked" (selected)
+     **************************************************/
+
+    /* TODO: this references some color values, whereas it would be preferable
+     * to refer to some sort of "state" instead, color of which was
+     * configurable.  b/c these are just the default Buefy theme colors. */
+
+    tr.is-checked {
+        background-color: #7957d5;
+        color: white;
+    }
+
+    tr.is-checked:hover {
+        color: #363636;
+    }
+
+    tr.is-checked a {
+        color: white;
+    }
+
+    tr.is-checked:hover a {
+        color: #7957d5;
+    }
+
     /* ****************************** */
     /* forms */
     /* ****************************** */