We just rolled out a nifty automatic install for Shopify users. You no longer need to mess around with any code for installing the full page or widget styles. For the lightbox, you'll still need to manually install this yourself.
Here's the new Shopify install process:
Choose the style you want to install and click the dropdown menu:
Choose Shopify from the dropdown menu, then click the Install button:
Type in a page name that you want to install to. This will create a new page, it will not install to an existing page:
That's it! Your promotion is now installed to your store: