diff --git a/apps/ui/templates/dashboard.html b/apps/ui/templates/dashboard.html
index 7c9ebd4..e3832d4 100644
--- a/apps/ui/templates/dashboard.html
+++ b/apps/ui/templates/dashboard.html
@@ -1649,6 +1649,21 @@
                             <div class="group-card-title">${group.name}</div>
                             <div class="group-card-subtitle">${group.device_count} ${group.device_count === 1 ? 'Gerät' : 'Geräte'}</div>
                         </div>
+                        ${group.capabilities.brightness ? `
+                        <div class="brightness-control">
+                            <label class="brightness-label">
+                                <span>🔆 Helligkeit</span>
+                                <span class="brightness-value" id="group-brightness-${group.id}">50%</span>
+                            </label>
+                            <input type="range" 
+                                   min="0" 
+                                   max="100" 
+                                   value="50" 
+                                   class="brightness-slider"
+                                   id="slider-group-${group.id}"
+                                   oninput="updateGroupBrightnessDisplay('${group.id}', this.value)">
+                        </div>
+                        ` : ''}
                         <div class="group-card-actions">
                             <button class="group-button on" onclick="setGroup('${group.id}', 'on', this)">
                                 Alle An
@@ -1669,6 +1684,14 @@
             }
         }
         
+        // Update group brightness display value
+        function updateGroupBrightnessDisplay(groupId, value) {
+            const display = document.getElementById(`group-brightness-${groupId}`);
+            if (display) {
+                display.textContent = `${value}%`;
+            }
+        }
+        
         // Execute group action
         async function setGroup(groupId, power, buttonElement) {
             const allButtons = buttonElement.parentElement.querySelectorAll('button');
@@ -1677,14 +1700,23 @@
             const originalHTML = buttonElement.innerHTML;
             buttonElement.innerHTML = '<span class="spinner"></span>';
             
+            // Get brightness value if slider exists
+            const slider = document.getElementById(`slider-group-${groupId}`);
+            const brightness = slider ? parseInt(slider.value) : null;
+            
             try {
+                const payload = { power };
+                if (brightness !== null && power === 'on') {
+                    payload.brightness = brightness;
+                }
+                
                 const response = await fetch(api(`/groups/${groupId}/set`), {
                     method: 'POST',
                     headers: { 'Content-Type': 'application/json' },
                     body: JSON.stringify({
                         action: {
                             type: 'power',
-                            payload: { power }
+                            payload: payload
                         }
                     })
                 });