Read More / Read Less for a text box

Hi, I have a text box that's rather long and I'm looking for a way to add just a read more / read less to it. I've looked through a lot of posts on here, but can't seem to find the right solution. 

This is what I'm trying to achieve, and I injected the code in the footer, but it didn't seem to work, so I'm thinking it's probably outdated? I know that there's summary blocks, but I don't like how they format, and I already have everything formatted already the way I like it, and the read more is a link to a different page on summary blocks. I just want to be able to click read more, have it expand, and then read less and have it contract. I hope that makes sense. 

You can share link to page where you use Text Block & let me know which text you want to add read more/read less text?