diff --git a/api/bulk_operation.php b/api/bulk_operation.php
index e94b21e..5c5b9f4 100644
--- a/api/bulk_operation.php
+++ b/api/bulk_operation.php
@@ -50,12 +50,14 @@ if (!$operationType || empty($ticketIds)) {
     exit;
 }
 
-// Validate ticket IDs are integers
-foreach ($ticketIds as $ticketId) {
-    if (!is_numeric($ticketId)) {
-        echo json_encode(['success' => false, 'error' => 'Invalid ticket ID format']);
-        exit;
-    }
+// Validate ticket IDs are positive integers
+$ticketIds = array_values(array_filter(array_map(function($id) {
+    $int = (int)$id;
+    return ($int > 0 && (string)$int === (string)$id) ? $int : null;
+}, $ticketIds)));
+if (empty($ticketIds)) {
+    echo json_encode(['success' => false, 'error' => 'No valid ticket IDs provided']);
+    exit;
 }
 
 // Use centralized database connection
diff --git a/assets/js/ticket.js b/assets/js/ticket.js
index 6ac03bd..efb6b27 100644
--- a/assets/js/ticket.js
+++ b/assets/js/ticket.js
@@ -475,10 +475,10 @@ function showDependencyError(message) {
     const dependentsList = document.getElementById('dependentsList');
 
     if (dependenciesList) {
-        dependenciesList.innerHTML = `<p class="text-amber">${lt.escHtml(message)}</p>`;
+        dependenciesList.innerHTML = `<p class="lt-text-amber">${lt.escHtml(message)}</p>`;
     }
     if (dependentsList) {
-        dependentsList.innerHTML = `<p class="text-amber">${lt.escHtml(message)}</p>`;
+        dependentsList.innerHTML = `<p class="lt-text-amber">${lt.escHtml(message)}</p>`;
     }
 }
 
@@ -512,7 +512,7 @@ function renderDependencies(dependencies) {
                         <span class="dependency-title">${lt.escHtml(dep.title)}</span>
                         <span class="status-badge ${statusClass}">${lt.escHtml(dep.status)}</span>
                     </div>
-                    <button data-action="remove-dependency" data-dependency-id="${dep.dependency_id}" class="btn btn-small">REMOVE</button>
+                    <button data-action="remove-dependency" data-dependency-id="${dep.dependency_id}" class="lt-btn lt-btn-sm">REMOVE</button>
                 </div>`;
             });
 
@@ -521,7 +521,7 @@ function renderDependencies(dependencies) {
     }
 
     if (!hasAny) {
-        html = '<p class="text-muted-green">No dependencies configured.</p>';
+        html = '<p class="lt-text-muted">No dependencies configured.</p>';
     }
 
     container.innerHTML = html;
@@ -532,7 +532,7 @@ function renderDependents(dependents) {
     if (!container) return;
 
     if (dependents.length === 0) {
-        container.innerHTML = '<p class="text-muted-green">No tickets depend on this one.</p>';
+        container.innerHTML = '<p class="lt-text-muted">No tickets depend on this one.</p>';
         return;
     }
 
@@ -546,7 +546,7 @@ function renderDependents(dependents) {
                 </a>
                 <span class="dependency-title">${lt.escHtml(dep.title)}</span>
                 <span class="status-badge ${statusClass}">${lt.escHtml(dep.status)}</span>
-                <span class="dependency-title text-amber">(${lt.escHtml(dep.dependency_type)})</span>
+                <span class="dependency-title lt-text-amber">(${lt.escHtml(dep.dependency_type)})</span>
             </div>
         </div>`;
     });
@@ -756,11 +756,11 @@ function loadAttachments() {
             if (data.success) {
                 renderAttachments(data.attachments || []);
             } else {
-                container.innerHTML = '<p class="text-muted-green">Error loading attachments.</p>';
+                container.innerHTML = '<p class="lt-text-muted">Error loading attachments.</p>';
             }
         })
         .catch(error => {
-            container.innerHTML = '<p class="text-muted-green">Error loading attachments.</p>';
+            container.innerHTML = '<p class="lt-text-muted">Error loading attachments.</p>';
         });
 }
 
@@ -769,7 +769,7 @@ function renderAttachments(attachments) {
     if (!container) return;
 
     if (attachments.length === 0) {
-        container.innerHTML = '<p class="text-muted-green">No files attached to this ticket.</p>';
+        container.innerHTML = '<p class="lt-text-muted">No files attached to this ticket.</p>';
         return;
     }
 
@@ -799,8 +799,8 @@ function renderAttachments(attachments) {
                 </div>
             </div>
             <div class="attachment-actions">
-                <a href="/api/download_attachment.php?id=${att.attachment_id}" class="btn btn-small" title="Download">⬇</a>
-                <button data-action="delete-attachment" data-attachment-id="${att.attachment_id}" class="btn btn-small btn-danger" title="Delete">✕</button>
+                <a href="/api/download_attachment.php?id=${att.attachment_id}" class="lt-btn lt-btn-sm" title="Download">⬇</a>
+                <button data-action="delete-attachment" data-attachment-id="${att.attachment_id}" class="lt-btn lt-btn-sm lt-btn-danger" title="Delete">✕</button>
             </div>
         </div>`;
     });
@@ -1123,8 +1123,8 @@ function editComment(commentId) {
                 Markdown
             </label>
             <div class="comment-edit-buttons">
-                <button type="button" class="btn btn-small" data-action="save-edit-comment" data-comment-id="${commentId}">SAVE</button>
-                <button type="button" class="btn btn-secondary btn-small" data-action="cancel-edit-comment" data-comment-id="${commentId}">CANCEL</button>
+                <button type="button" class="lt-btn lt-btn-sm" data-action="save-edit-comment" data-comment-id="${commentId}">SAVE</button>
+                <button type="button" class="lt-btn lt-btn-ghost lt-btn-sm" data-action="cancel-edit-comment" data-comment-id="${commentId}">CANCEL</button>
             </div>
         </div>
     `;
@@ -1279,7 +1279,7 @@ function showReplyForm(commentId, userName) {
                     <span>Markdown</span>
                 </label>
                 <div class="reply-buttons">
-                    <button type="button" class="btn btn-small" data-action="submit-reply" data-parent-id="${commentId}">REPLY</button>
+                    <button type="button" class="lt-btn lt-btn-sm" data-action="submit-reply" data-parent-id="${commentId}">REPLY</button>
                 </div>
             </div>
         </div>
diff --git a/models/AttachmentModel.php b/models/AttachmentModel.php
index 7291719..82c4626 100644
--- a/models/AttachmentModel.php
+++ b/models/AttachmentModel.php
@@ -21,7 +21,7 @@ class AttachmentModel {
                 ORDER BY a.uploaded_at DESC";
 
         $stmt = $this->conn->prepare($sql);
-        $stmt->bind_param("s", $ticketId);
+        $stmt->bind_param("i", $ticketId);
         $stmt->execute();
         $result = $stmt->get_result();
 
@@ -61,7 +61,7 @@ class AttachmentModel {
                 VALUES (?, ?, ?, ?, ?, ?)";
 
         $stmt = $this->conn->prepare($sql);
-        $stmt->bind_param("sssisi", $ticketId, $filename, $originalFilename, $fileSize, $mimeType, $uploadedBy);
+        $stmt->bind_param("issisi", $ticketId, $filename, $originalFilename, $fileSize, $mimeType, $uploadedBy);
         $result = $stmt->execute();
 
         if ($result) {
@@ -97,7 +97,7 @@ class AttachmentModel {
                 WHERE ticket_id = ?";
 
         $stmt = $this->conn->prepare($sql);
-        $stmt->bind_param("s", $ticketId);
+        $stmt->bind_param("i", $ticketId);
         $stmt->execute();
         $result = $stmt->get_result();
         $row = $result->fetch_assoc();
@@ -113,7 +113,7 @@ class AttachmentModel {
         $sql = "SELECT COUNT(*) as count FROM ticket_attachments WHERE ticket_id = ?";
 
         $stmt = $this->conn->prepare($sql);
-        $stmt->bind_param("s", $ticketId);
+        $stmt->bind_param("i", $ticketId);
         $stmt->execute();
         $result = $stmt->get_result();
         $row = $result->fetch_assoc();
diff --git a/models/CommentModel.php b/models/CommentModel.php
index efb5980..b38e0ca 100644
--- a/models/CommentModel.php
+++ b/models/CommentModel.php
@@ -240,7 +240,7 @@ class CommentModel {
             return ['success' => false, 'error' => 'Comment not found'];
         }
 
-        if ($comment['user_id'] != $userId && !$isAdmin) {
+        if ($comment['user_id'] !== (int)$userId && !$isAdmin) {
             return ['success' => false, 'error' => 'You do not have permission to edit this comment'];
         }
 
@@ -286,7 +286,7 @@ class CommentModel {
             return ['success' => false, 'error' => 'Comment not found'];
         }
 
-        if ($comment['user_id'] != $userId && !$isAdmin) {
+        if ($comment['user_id'] !== (int)$userId && !$isAdmin) {
             return ['success' => false, 'error' => 'You do not have permission to delete this comment'];
         }