How to make product variants side-by-side instead of dropdown

[Hetko]

How can I create products variants which are side by side instead of in a dropdown menu? 

 

I've seen it here that it is possible:

http://venedor.promokit.eu/brown/de/fashion/9-off-white-lace-print.html

(It's a Prestashop Template and the sizes are side-by-side)

 

I have searched in the market place but can't find a module.

Does anyone know which is used for this or how it is possible?

 

Thanks for your help!

Edited August 2, 2015 by Hetko (see edit history)