This layout is a basic example of a mulitcolomn responsive layout using the flexbox css.

Using the flexbox css makes it very easy to deal with the different aspect ratios of the images,resulting in different height of the container element.
The flexbox css is supported on al major modern browsers but it ain't perfect yet.

To create your own layout copy this file:
/components/com_datafeeds/views/items/tmpl/default_flexbox.php
to
template/jr_leotian/html/com_datafeeds/items
and modify the file there. Do not modify the file on the current location

• More on creating a custom layout
• All about the flexbox css

On older browsers the <li> elements will have different sizes if the images have different aspect ratios resulting in gaps.