Enforce level background colours now use CSS custom properties from CE.

config_enforce_devel.libraries.yml

@@ -4,3 +4,6 @@ config-enforce-devel:
     component:
        css/config-enforce-devel.css: {}
        css/config-enforce-devel-toolbar.css: {}
+  dependencies:
+    # Needed for CSS custom properties definined therein.
+    - config_enforce/config-enforce

css/config-enforce-devel.css

@@ -4,15 +4,15 @@ form.config-enforce-enforced-configs-form tr.enforced a {
 }
 form.config-enforce-enforced-configs-form tr.enforced.level-20,
 form.config-enforce-enforced-configs-form tr.enforced.level-20 li {
-    background-color: paleGreen;
+  background-color: var(--config-enforce-background-colour-level-20);
 }
 form.config-enforce-enforced-configs-form tr.enforced.level-10,
 form.config-enforce-enforced-configs-form tr.enforced.level-10 li {
-    background-color: lightBlue;
+  background-color: var(--config-enforce-background-colour-level-10);
 }
 form.config-enforce-enforced-configs-form tr.enforced.level-0,
 form.config-enforce-enforced-configs-form tr.enforced.level-0 li {
-    background-color: lightGrey;
+  background-color: var(--config-enforce-background-colour-level-0);
 }
 
 form.config-enforce-devel-modal div.form-wrapper,