.htaccess display error pages on http errors

In your htaccess file add the below lines and save to show error pages on Http errors (404, 403 etc)

ErrorDocument 403 /errors/404.html
ErrorDocument 404 /errors/404.html

Here, errors is the folder where you can keep your Http error pages .

If the requested resource doesn't exist, default to index.html

RewriteRule ^ /index.html