Jetpack Tiled Galleries

The width of the tiled or square tiles display in my jetpack carousel leaves a white space on the side. I would like it to maximize available width, please.

Sample: https://www.lemisstache.com/2015/02/22/miao-first-cat-cafe-in-manila/

Please note that I already have this on my functions.php:

if ( ! isset( $content_width ) ) $content_width = 640;

thank you