Lightning gives you the tools to take real control of the layout of your site's content. It integrates the Panelizer module, which gives you a very flexible drag-and-drop interface with which you can set up the look of your content.

Panelizer is enabled per view mode. A view mode is, essentially, a single layout for a content type. A content type can have any number of view modes. Out of the box, content types will have two view modes: Default and Teaser. Default is the view mode used when you visit a single piece of content on its own page. Teaser is generally used when viewing a list of content (each piece of content in the list is displayed in the Teaser view mode).

With the exception of the Landing Page content type, Panelizer is not enabled for any view mode out of the box. Here's how to enable it for a content type:

1. Visit the Manage > Structure > Content types page.
2. Click the drop button for the content type you'd like to enable Panelizer on, and select "Manage display".
3. Scroll down to the bottom of the table, and check the box labeled "Panelize this view mode". Another checkbox will appear below it, labeled "Allow custom overrides of each entity". Check it as well.
4. Click the Save button.

It's important to understand that any piece of panelized content will take its layout from one of two possible places. It can use the default layout for its content type, or it can use a layout that has been set up for just that one piece of content (this is referred to as a "custom" or "overridden" layout).

At the moment, when you save changes to the layout of any piece of panelized content, you're presented with the option to save your changes as the defaults for that content type, or as a custom layout that piece of content only. It's possible, however, to set up permissions to ensure that the default layout cannot be changed that way. This is desirable if you have a content type wherein every piece of content should use its own custom layout -- landing pages being a prime example. To disable the ability to set the default layout, you will want to tweak the permissions named something like "Content Landing page: Administer Panelizer default panels, allowed content and settings".

(For the record, we're aware that this is potentially very confusing and a less than ideal user experience. Work is underway to clean this up enormously, and it will change before Lightning comes out of beta.)