Input tag not working on specific site: What now? [on hold]

Okay, I'm at my wit's end. I am not an advanced coder by any stretch, so maybe the solution here is obvious. I'll take any help I can get.

I am working on a project with a very specific website that runs off the old Livejournal engine. I am trying to employ fairly straightforward snippets of code involving the input tag check-box/radio button hack, but the website is refusing to acknowledge them. I thought it was just my code, so I went for something simple someone else wrote, which was proven to work on Codepen. Doesn't matter if it's my code or someone else's, the site is not rendering it. All I get is <input ... > followed by the content of the menu/tabs/whatever.

Which begs the question... are there any 'click' alternatives -- I want to stay far away from hovers because of mobile users -- for creating tabs, responsive menu drawers, etc. that aren't JS (because I know for sure the site strips JS) and aren't associated with the input tag?

Or, alternatively, does anyone have any ideas about forcing this site to deal with input tags?