The present disclosure generally relates to navigating a collection of media items. In accordance with one embodiment, a device displays a plurality of content items in a first layout, including a first content item at a first aspect ratio and a first size, a second content item, and a third content item. While displaying the plurality of content items in the first layout, the device detects a user input that includes a gesture, wherein the user input corresponds to a request to change a size of the first content item. In response to detecting the user input, and as the gesture progresses, the device changes the size of the first content item from the first size to a second size while concurrently gradually changing an aspect ratio of the first content item from the first aspect ratio to a second aspect ratio.