Collapse text

I'm such a rebel, two questions at once. Anyway, I'm using Harlowe and I haven't found anything by Google, so I may as well ask. What kind of code can I use to make some text collapsible?
In this game, FWAA, I'm using this sidebar code and within it is display: displaying the contents of an inventory. It's really long, though, so can I make it so that it's able to be opened and closed at leisure?