We're going to use a plugin called (appropriately) Better Preview. Here's how you do it:
- Download the Better Preview plugin from NoNumber.nl.
- In the administration area of your Joomla site, go to Extensions >> Install / Uninstall and upload the file to install. The plugin will publish automatically.
- Go to write a new article and a button saying "Preview" will appear in the top-right of your screen.
- Click that link to see the article with the correct template, modules and styles.
One extra benefit is that you'll also be able to see the URL of page. Joomla's normal preview appears in a pop-up so you don't know where it will be located.