diff --git a/administrator/templates/atum/scss/vendor/joomla-custom-elements/joomla-alert.scss b/administrator/templates/atum/scss/vendor/joomla-custom-elements/joomla-alert.scss
index 76903babfda5c..3387552870cad 100644
--- a/administrator/templates/atum/scss/vendor/joomla-custom-elements/joomla-alert.scss
+++ b/administrator/templates/atum/scss/vendor/joomla-custom-elements/joomla-alert.scss
@@ -26,6 +26,10 @@
     background: var(--alert-accent-color, transparent);
   }
 
+  .alert-wrapper {
+    width: 100%;
+  }
+
   .alert-link {
     color: var(--success, inherit);
   }
@@ -90,5 +94,9 @@
         padding: .3rem .3rem .3rem 2rem;
       }
     }
+
+    .alert-message:not(:first-of-type) {
+      border-top: 1px solid var(--alert-accent-color);
+    }
   }
 }
diff --git a/build/media_source/system/js/core.es6/message.es6 b/build/media_source/system/js/core.es6/message.es6
index 981cd42a59c06..d0545f090233c 100644
--- a/build/media_source/system/js/core.es6/message.es6
+++ b/build/media_source/system/js/core.es6/message.es6
@@ -82,11 +82,12 @@
       }
 
       // Add messages to the message box
+      messageWrapper = document.createElement('div');
+      messageWrapper.className = 'alert-wrapper';
       typeMessages.forEach((typeMessage) => {
-        messageWrapper = document.createElement('div');
-        messageWrapper.innerHTML = `<div class="alert-message">${typeMessage}</div>`;
-        messagesBox.appendChild(messageWrapper);
+        messageWrapper.innerHTML += `<div class="alert-message">${typeMessage}</div>`;
       });
+      messagesBox.appendChild(messageWrapper);
 
       messageContainer.appendChild(messagesBox);
     });
diff --git a/layouts/joomla/system/message.php b/layouts/joomla/system/message.php
index a319f23564460..dec8e51c8e679 100644
--- a/layouts/joomla/system/message.php
+++ b/layouts/joomla/system/message.php
@@ -46,7 +46,7 @@
 				<joomla-alert type="<?php echo $alert[$type] ?? $type; ?>" dismiss="true">
 					<?php if (!empty($msgs)) : ?>
 						<div class="alert-heading"><?php echo Text::_($type); ?></div>
-						<div>
+						<div class="alert-wrapper">
 							<?php foreach ($msgs as $msg) : ?>
 								<div class="alert-message"><?php echo $msg; ?></div>
 							<?php endforeach; ?>
diff --git a/templates/cassiopeia/scss/vendor/joomla-custom-elements/joomla-alert.scss b/templates/cassiopeia/scss/vendor/joomla-custom-elements/joomla-alert.scss
index bed2eab255e7d..a9fd50b2c7001 100644
--- a/templates/cassiopeia/scss/vendor/joomla-custom-elements/joomla-alert.scss
+++ b/templates/cassiopeia/scss/vendor/joomla-custom-elements/joomla-alert.scss
@@ -26,6 +26,10 @@
     background: var(--alert-accent-color, transparent);
   }
 
+  .alert-wrapper {
+    width: 100%;
+  }
+
   .alert-link {
     color: var(--success, inherit);
   }
@@ -90,5 +94,9 @@
         padding: .3rem .3rem .3rem 2rem;
       }
     }
+
+    .alert-message:not(:first-of-type) {
+      border-top: 1px solid var(--alert-accent-color);
+    }
   }
 }