Use cache manifest in wordpress themes
Easy way to generate a html5 cache manifest file for wordpress themes.Activate the plugin in WordPress Plugin Panel and the plugin will create a cache manifest file in your current blog theme’s directory.
Your blog site served with the content type text/cache-manifest. If you are running an Apache-based web server, you can probably just put an AddType directive in the .htaccess file at the root of your web directory:
AddType text/cache-manifest .manifest