CSS: Margin in Mobile & Top Menu Stuck in Mobile

I need your kind help please. My website is tripmagics.com

There is problem of top margin in mobile. In mobile top heading about us is hiding behind top menu. In desktop/laptop its ok. https://tripmagics.com/about-us

And also if you go to destination in top menu in mobile its not scrolling down, it’s stuck. In desktop its ok.

Kindly tell in which file/css etc I need to add which code or line of code

Really appreciate. I thank you in advance. Good day

I tried to add @media only screen and (max-width: in all screens size but its not working