diff --git a/src/main/resources/META-INF/frontend/styles/fc-days-of-week-selector-styles.css b/src/main/resources/META-INF/frontend/styles/fc-days-of-week-selector-styles.css
index ba046f3..324ba05 100644
--- a/src/main/resources/META-INF/frontend/styles/fc-days-of-week-selector-styles.css
+++ b/src/main/resources/META-INF/frontend/styles/fc-days-of-week-selector-styles.css
@@ -36,12 +36,12 @@ vaadin-button.fc-days-of-week-selector-button[theme~='primary'][disabled]::part(
 }
 
 vaadin-button.fc-days-of-week-selector-button[disabled].readOnly{
-    color: var(--lumo-secondary-text-color);
+    color: var(--lumo-secondary-text-color, var(--vaadin-text-color-secondary));
     background: transparent;
 }
 
 vaadin-button.fc-days-of-week-selector-button[theme~='primary'][disabled].readOnly {
-    border: var(--vaadin-input-field-readonly-border, 1px dashed var(--lumo-contrast-30pct));
+    border: var(--vaadin-input-field-readonly-border, 1px dashed var(--lumo-contrast-30pct, var(--vaadin-border-color)));
 }
 
 vaadin-button.fc-days-of-week-selector-button[focus-ring]{
diff --git a/src/main/resources/META-INF/frontend/styles/fc-days-of-week-selector.css b/src/main/resources/META-INF/frontend/styles/fc-days-of-week-selector.css
index c0e1dfc..5de28ea 100644
--- a/src/main/resources/META-INF/frontend/styles/fc-days-of-week-selector.css
+++ b/src/main/resources/META-INF/frontend/styles/fc-days-of-week-selector.css
@@ -39,12 +39,12 @@ vaadin-button.fc-days-of-week-selector-button[theme~='primary'][disabled]::part(
 }
 
 vaadin-button.fc-days-of-week-selector-button[disabled].readOnly{
-    color: var(--lumo-secondary-text-color);
+    color: var(--lumo-secondary-text-color, var(--vaadin-text-color-secondary));
     background: transparent;
 }
 
 vaadin-button.fc-days-of-week-selector-button[theme~='primary'][disabled].readOnly {
-    border: var(--vaadin-input-field-readonly-border, 1px dashed var(--lumo-contrast-30pct));
+    border: var(--vaadin-input-field-readonly-border, 1px dashed var(--lumo-contrast-30pct, var(--vaadin-border-color)));
 }
 
 vaadin-button.fc-days-of-week-selector-button[focus-ring]{
diff --git a/src/main/resources/META-INF/frontend/styles/vaadin-context-menu-list-box.css b/src/main/resources/META-INF/frontend/styles/vaadin-context-menu-list-box.css
index 85e4a22..92c5117 100644
--- a/src/main/resources/META-INF/frontend/styles/vaadin-context-menu-list-box.css
+++ b/src/main/resources/META-INF/frontend/styles/vaadin-context-menu-list-box.css
@@ -19,7 +19,7 @@
  */
  
 :host([theme~='fc-day-of-week-selector-context-menu']) [part~="items"]	{
-	padding: 0 var(--lumo-space-xs);
+	padding: 0 var(--lumo-space-xs, var(--vaadin-padding-xs));
 	display: inline-flex;
-	gap: var(--fc-days-of-week-selector-button-space, var(--lumo-space-m));
+	gap: var(--fc-days-of-week-selector-button-space, var(--lumo-space-m, var(--vaadin-padding-m)));
 }
\ No newline at end of file
diff --git a/src/main/resources/META-INF/resources/frontend/src/fc-days-of-week-selector.ts b/src/main/resources/META-INF/resources/frontend/src/fc-days-of-week-selector.ts
index 477dd31..6f3d744 100644
--- a/src/main/resources/META-INF/resources/frontend/src/fc-days-of-week-selector.ts
+++ b/src/main/resources/META-INF/resources/frontend/src/fc-days-of-week-selector.ts
@@ -64,7 +64,7 @@ export class DaysOfWeekSelector extends ResizeMixin(ThemableMixin(LitElement)) {
                 flex-wrap: nowrap;
                 overflow: hidden;
                 align-items: center;
-                gap: var(--fc-days-of-week-selector-button-space, var(--lumo-space-m));
+                gap: var(--fc-days-of-week-selector-button-space, var(--lumo-space-m, var(--vaadin-gap-m, 0.5rem)));
             }
 
             [part="overflow-badge"] {
@@ -96,7 +96,7 @@ export class DaysOfWeekSelector extends ResizeMixin(ThemableMixin(LitElement)) {
             }
 
             [part="container"] vaadin-context-menu {
-                margin-left: calc(var(--lumo-space-s) * -1);
+                margin-left: calc(var(--lumo-space-s, var(--vaadin-gap-s, 8px)) * -1);
             }
 
             ::slotted([slot="overflowIcon"]) {
diff --git a/src/test/java/com/flowingcode/vaadin/addons/AppShellConfiguratorImpl.java b/src/test/java/com/flowingcode/vaadin/addons/AppShellConfiguratorImpl.java
index 5f67d7b..97739b4 100644
--- a/src/test/java/com/flowingcode/vaadin/addons/AppShellConfiguratorImpl.java
+++ b/src/test/java/com/flowingcode/vaadin/addons/AppShellConfiguratorImpl.java
@@ -19,10 +19,16 @@
  */
 package com.flowingcode.vaadin.addons;
 
+import com.flowingcode.vaadin.addons.demo.DynamicTheme;
 import com.vaadin.flow.component.page.AppShellConfigurator;
-import com.vaadin.flow.theme.Theme;
+import com.vaadin.flow.server.AppShellSettings;
 
-@Theme
 public class AppShellConfiguratorImpl implements AppShellConfigurator {
 
+  @Override
+  public void configurePage(AppShellSettings settings) {
+    if (DynamicTheme.isFeatureSupported()) {
+      DynamicTheme.LUMO.initialize(settings);
+    }
+  }
 }