[NIFI-13096] restore box-shadows for dark mode (#8699)

This closes #8699 
diff --git a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/pages/flow-designer/ui/canvas/footer/_footer.component-theme.scss b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/pages/flow-designer/ui/canvas/footer/_footer.component-theme.scss
index 4a30c4c..c72f59c 100644
--- a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/pages/flow-designer/ui/canvas/footer/_footer.component-theme.scss
+++ b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/pages/flow-designer/ui/canvas/footer/_footer.component-theme.scss
@@ -31,7 +31,7 @@
     $on-surface-lighter: utils.get-on-surface($nifi-theme-color-config, lighter);
 
     .breadcrumb-container {
-        box-shadow: 0 1px 6px $on-surface-lighter;
+        box-shadow: 0 3px 6px rgba(0, 0, 0, 0.25);
         background-color: $nifi-theme-surface-palette-lighter;
         border-top: 1px solid $on-surface-lighter;
     }
diff --git a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/pages/flow-designer/ui/canvas/graph-controls/navigation-control/_navigation-control.component-theme.scss b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/pages/flow-designer/ui/canvas/graph-controls/navigation-control/_navigation-control.component-theme.scss
index ab7a8f8..060c78c 100644
--- a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/pages/flow-designer/ui/canvas/graph-controls/navigation-control/_navigation-control.component-theme.scss
+++ b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/pages/flow-designer/ui/canvas/graph-controls/navigation-control/_navigation-control.component-theme.scss
@@ -32,7 +32,7 @@
     $on-surface-lighter: utils.get-on-surface($nifi-theme-color-config, lighter);
 
     div.navigation-control {
-        box-shadow: 0 1px 6px $on-surface-lighter;
+        box-shadow: 0 1px 6px rgba(0, 0, 0, 0.25);
         background-color: $nifi-theme-surface-palette-lighter;
         border: 1px solid $on-surface-lighter;
 
diff --git a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/pages/flow-designer/ui/canvas/graph-controls/operation-control/_operation-control.component-theme.scss b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/pages/flow-designer/ui/canvas/graph-controls/operation-control/_operation-control.component-theme.scss
index 6a22429..3d1cec3 100644
--- a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/pages/flow-designer/ui/canvas/graph-controls/operation-control/_operation-control.component-theme.scss
+++ b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/pages/flow-designer/ui/canvas/graph-controls/operation-control/_operation-control.component-theme.scss
@@ -32,7 +32,7 @@
     $on-surface-highlight: utils.get-on-surface($nifi-theme-color-config, highlight);
 
     div.operation-control {
-        box-shadow: 0 1px 6px $on-surface-lighter;
+        box-shadow: 0 1px 6px rgba(0, 0, 0, 0.25);
         background-color: $nifi-theme-surface-palette-lighter;
         border: 1px solid $on-surface-lighter;
 
diff --git a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/ui/common/context-menu/_context-menu.component-theme.scss b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/ui/common/context-menu/_context-menu.component-theme.scss
index abcf3a5..a144235 100644
--- a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/ui/common/context-menu/_context-menu.component-theme.scss
+++ b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/app/ui/common/context-menu/_context-menu.component-theme.scss
@@ -40,7 +40,7 @@
     div.context-menu {
         background-color: $nifi-theme-surface-palette-darker;
         border: 1px solid $material-theme-primary-palette-default;
-        box-shadow: 0 3px 6px $on-surface-lighter;
+        box-shadow: 0 3px 6px rgba(0, 0, 0, 0.25);
 
         .context-menu-item:hover {
             background-color: $on-surface-highlight;
diff --git a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/assets/styles/_app.scss b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/assets/styles/_app.scss
index bebff29..b1cdb48 100644
--- a/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/assets/styles/_app.scss
+++ b/nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-frontend/src/main/nifi/src/assets/styles/_app.scss
@@ -337,7 +337,7 @@
     }
 
     .cdk-drag-preview {
-        box-shadow: 0 3px 6px $on-surface-lighter;
+        box-shadow: 0 3px 6px rgba(0, 0, 0, 0.25);
     }
 
     .has-errors,
@@ -349,13 +349,13 @@
     .tooltip {
         background-color: $nifi-theme-surface-palette-lighter;
         border-color: $on-surface-primary-default;
-        box-shadow: 0 2px 5px $on-surface-lighter;
+        box-shadow: 0 2px 5px rgba(0, 0, 0, 0.25);
         color: $on-surface-primary-default;
     }
 
     .property-editor {
         background-color: $nifi-theme-surface-palette-darker;
-        box-shadow: 0 2px 5px $on-surface-lighter;
+        box-shadow: 0 2px 5px rgba(0, 0, 0, 0.25);
     }
 
     ngx-skeleton-loader .skeleton-loader {