Navigation Menu Problems

Hello!
Let’s give this another try…
I’m am having trouble with my navigation menu. I want to make the bar transparent and I was able to by adding this css below:
.main-navigation:not(.is_stuck) {
position: fixed;
left: 0;
right: 0;
}
But as you can see on my site it does not only make the menu transparent, it also makes it a sticky/fixed menu. When I try disabling that feature, nothing changes. Is there a different CSS I could use or any other recommendations?
I’m also having trouble with the way the menu appears on mobile. It is auto expanding and does not look good.

Thanks for the help!!
See my website below (on mobile and desktop) :

HOME