How to implement scaling of heterogeneous images in a resizeable block?

Question

JavaScript

Hello, a question for front-end developers.
There is a site http://www.delta-search.com, where you can create start pages, if you follow the link there and create your own such page, then the widget appears by default (screenshot habrastorage.org/storage3/167/9ed/853/ 1679ed85379683fc1cdc69f2124194e3.jpg ) links with icons, when this block is stretched, the pictures are scaled, while the proportions and sizes of the icons are different.
How can this be implemented?

Answer 1

If I understand correctly, then background-size: contain

Answer 2

Also, if I understand correctly.
jsfiddle.net/e5sTL/