XF 1.5 Toggle CSS Elements through Button

Hi. I'd like to setup a way for my users to toggle some CSS elements (such as avatar shape, board logo height, etc.) by clicking a link/button from the userbar. For example, on my old site, users were able to toggle the text-shadow elements on names. This is visible here: https://web.archive.org/web/20170506060241/http://lakevalor.net/ (click the "B" fontawesome icon on the userbar).

Changes would stay when the page was refreshed or clicked out of. Is something like this possible with xenForo? And if so, how would I go about doing it?