修改部分参数

Co-authored-by: Copilot <copilot@github.com>

app/templates/printer/control.html

@@ -17,8 +17,15 @@
             <div class="card-header bg-dark text-light fw-bold rounded-top">
                 <i class="bi bi-camera-video me-1"></i>{{ _('Live Webcam') }}
             </div>
-            <div class="card-body p-0 ratio ratio-16x9">
+            <div class="card-body p-0 ratio ratio-16x9 bg-secondary bg-opacity-25 d-flex align-items-center justify-content-center">
+                {% if current_user.is_guest %}
+                <div class="text-center text-dark">
+                    <i class="bi bi-lock-fill display-4 d-block mb-3"></i>
+                    <h5 class="mb-0">{{ _('Please login to view the webcam stream.') }}</h5>
+                </div>
+                {% else %}
                 <img src="{{ webcam_url }}" alt="{{ _('Loading webcam stream...') }}" class="w-100 h-100 object-fit-cover">
+                {% endif %}
             </div>
         </div>
     </div>