Code Review, my project(landing page, Html,CSS,Js,gsap). "KillerWhale" Surfing school responsive website.

Hello, Mario. I could divide it in two segments, pros and cons.
First cons:

1. You can put more effort in responsive, I checked some problem arise with some device most importantly (760px-568px) viewport devices.
2. I believe you could follow DRY principle in your JS file though I don't know your JS skill weather you are beginner or just on other level. For this you can go with any design pattern. If you don't know what is design pattern is, please do some query on it.

Now pros:

1. You tried to use BEM naming convention, which looks very professional with your markup.
2. You use SCSS with it's super cool features like variable, mixin I appreciate it.
3. Animation is good seems to me.

All of points here from my perception don't take it personally please, stay healthy.
Happy hacking.