All custom CSS stopped working

I am pretty new to squarespace but I've nearly completed the redesign of my homepage in the Mentor template and now all my custom CSS stopped working. No idea what happened. Even basic code like #url-slug {background-color: black} no longer works. 

https://julienlubrique.com/category/sites-de-fetichisme-et-bdsm/

Is there something I'm missing? 

Hi,

Can you share link to your site? Difficult to know the cause without checking site url.

Or can you post all code here? (click <> icon then paste code)