Custom Css doesn't work when outside the custom page

Site URL: https://elizavolk-healingarts.squarespace.com/

Hello there,

I am trying to find a way to fix this : I added several scheduling buttons in my website (with markdown). I changed the style directly in it and in the custom css too to have the desired design. But for some reason, it applies only when I am in the custom css page and as soon as I leave it and refresh the page, a pink-ish background appears in the buttons. I go back to the custom page, the effects come back. etc etc... It is driving me crazy, please help if you have any explanation ! 🙏🏻

Here are the file attached: 

I wish you can see my happiness! Thank you so much you really are the best, you made my day 🙏🏻