Why Is The Second Jquery Code Part / New Css Part I Added Causing The First Jquery Code Not To Work On My Page

Ok so to improve my skills I decided to build a 'Play Market' responcive page. I built the search bar with the scroll effect (hides when scrolling down - displays when scrolling u

Solution 1:

I found the problem. on my code I had the body with 100% height. I gave it 1000px and it started working again. I have no clue why this is happening. if anybody knows I will be happy to hear :)