This is my first react project which I did by watching youtube tutorial video. Just because of this is a project from youtube tutorial video,I don't want you to assume that I copied and pasted the code.It took me a time to understand the algorithm.Because of this project, I understand the react better than I used to be. This is the youtube tutorial video link: https://www.youtube.com/watch?v=u6gSSpfsoOQ&t=3022s

I add different condition inside the ternary operator in Header.jsx file's line no.7 . I changed the color of the card's box-shadow to red which is black in the tutorial video.It doesn't look good in dark mode that's why I changed it.