Where can I find css codes about menu items?

I want to find out witch css code I need to put this item not in the header but in menu item. Need to translate it so header is not the best convenient solution.

Here is the link for pic:

Its a Flatsome theme


the Button background color has used from your primary color settings in Appearance => Customizer. Some css has used from assets/css/flatsome.css. You can inspect the elements to see the css. About menu item you can check header settings. Also please check theme documentation. If you would like you can get in touch with the theme Author How to Contact your purchased theme Author, theme author will be happy to assist you.