Update use of Sass variables for better theming

Use Bootstrap color functions for theme-colors and grays instead
of directly referencing Sass variable to allow more flexible
theming.

Signed-off-by: Yoshie Muranaka <yoshiemuranaka@gmail.com>
Change-Id: Id08b77ff6df3bdf99400dcdfe964853706f1070f
diff --git a/src/components/Global/TableToolbar.vue b/src/components/Global/TableToolbar.vue
index 05b9669..2fbbd6c 100644
--- a/src/components/Global/TableToolbar.vue
+++ b/src/components/Global/TableToolbar.vue
@@ -79,7 +79,7 @@
 
 .toolbar-content {
   height: $toolbar-height;
-  background-color: $primary;
+  background-color: theme-color('primary');
   color: $white;
   position: absolute;
   left: 0;