You will need to write custom CSS, but collapsible trees are totally possible to do purely in CSS in any framework via a simple combination of checkboxes, labels, pseudo-classes and CSS combinators.

The `:checked` selector allows you to target checkboxes that are checked. So you can have a set of checkboxes (off screen with an absolute negative position or similar) that are controlled via a <label> element that wraps the + or - text in the tree. Then based on its state, you can target elements directly afterward to be expanded or contracted using the CSS adjacent sibling combinator.

Checkboxes are neat because they provide state management natively in the DOM and you can do a lot via CSS based on that ;) Thus, you have pure HTML and CSS collapsible trees.