NIFI-6444 - FDS - Update expansion panel open arrow to be themeable

This closes #37

Signed-off-by: Scott Aslan <jaslan@jaslan-mbp15-hw14350.home>
diff --git a/platform/core/common/styles/_expansionPanels.scss b/platform/core/common/styles/_expansionPanels.scss
index 8ffc75a..2360b8c 100644
--- a/platform/core/common/styles/_expansionPanels.scss
+++ b/platform/core/common/styles/_expansionPanels.scss
@@ -44,7 +44,7 @@
 
   body[fds] td-expansion-panel .td-expansion-panel-header .td-expansion-panel-header-content mat-icon.td-expand-icon {
     font-size: 28px;
-    color: $blue-grey1;
+    color: $accentColor;
     font-weight: bold;
   }
 
@@ -54,7 +54,7 @@
     }
 
     &:hover:not(.mat-disabled) {
-      background: $blue4;
+      background: $accentColorHover;
     }
   }