A custom WordPress theme started from Automattic’s Underscores starter-theme with reference to an existing site that modeled the grid and card layout, though with very different graphics. Making the site attractive and usable at all screen sizes took some excellent art direction and design along with the obvious careful layout.
The theme makes extensive use of shortcodes to prevent edits from breaking the site, although the layout does constrain the content length in specific areas. Half of the visitors view the site on a screen 500px wide or smaller, so we spent a lot of time to get the mobile navigation right. The grid layout lends itself well to smaller screens — you stack the cards top to bottom rather than side to side — so that didn’t require a lot of detail design work, though the implementation had to be done carefully.