Need CSS code for Header: would like header to disappear when scroll down

hello! I'd like help with adding CSS code to my site (unless there is another option) so that my header disappears when I scroll down. 

Like this site: https://www.sanctuarycounselingaustin.com/

thank you!!

Thanks. Unfortunately I have 7.0 😞

I found that option in 7.0 and it worked! THANK YOU VERY MUCH

@roconnor78 You're welcome! Please mark as solution to help others.