Changing the Top Menu Style

I’m very impressed about this template and i’m going to use it on my private homepage (with Child).

I would like to change the style of the Top-Menu, where do i find it in CSS?
Is it all included in the area TOP_MOST_STYLES, or do i have to change it somewhere else?
Can i simply add the styling part in the child CSS and it’s getting loaded automatically instead of the master CSS content?

Thanks in advance