How to display items in 1 column on small screens

Hi,

I am using a layout with 3 items/columns which looks fine on most screens. But on smaller screen, the images/items which appear side by side are too small and with little space for the text to appear correctly. How can I make it so that the items appear one beloe the other in one column instead of in a row?

I tried using a media query and display:block on these: .related-gallery .gallery-item, dl, dt but it is not working.

Thank you for any help!

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