The easiest option I would suggest is adding a :focus state in your css (this styles a ‘selected’ button) however this might only work untill (any) other button is clicked, another option I would recommend is adding a jQuery snippet (through HTMLSnippet on the marketplace) and applying an onClick listener that adds a class for the extra styling.
It would result in this code into a snippet:
$(‘.class-of-clickable-item’).on(‘click’, function({
$(‘.class-of-item-to-change’).addClass(‘class-name-with-highlight’);
});
Using this you can also make it removable with .removeClass(‘class-to-remove’)