Bug with my theme

Hi team!

Please you can help me? I have an issue with the options of “Gallery” because displaying only with two columns, and the content is ready for enable three columns. At the best case, responsive.

Where is the problem?

The site in question is: http://www.biscottidicalvizzano.eu/

Very thanks!
Greetings

https://ww.wp.xz.cn/plugins/gallery-images/