I'm not great at CSS, but after a while i've finally figured out how this works (somewhat-) If you see something on my page you like/are wondering how to do it, I can answer those questions here :)

https://i.pinimg.com/originals/11/be/a1/11bea1ceae8ed1cff9cffa99b8e1158a.gif

so Ive learnt how to use CSS in the past but for the life of me i cant get my code to work? idk why its not working im pretty upset- how did yall add in the background images or is there some website yall use?