fix: Replace UContainer with div and apply width constraints directly in admin page

pages/admin.vue

@@ -25,7 +25,7 @@
       </div>
     </header>
 
-    <UContainer class="py-8 max-w-xl">
+    <div class="py-8 max-w-xl mx-auto px-4 sm:px-6 lg:px-8">
       <UCard>
         <template #header>
           <h2 class="text-xl font-semibold">Sermon Details</h2>
@@ -154,7 +154,7 @@
       <div v-if="successMessage" class="mt-4 p-4 bg-green-50 border border-green-200 rounded-lg">
         <p class="text-green-800">{{ successMessage }}</p>
       </div>
-    </UContainer>
+    </div>
   </div>
 </template>