How do i change the menu css

I have been working with all of the .main-menu css in the editor, but nothing at all is changing on the front end menu.

Can someone help me please?

I am also trying to allow the sub-menu to be displayed to but am getting nothing:

.main-menu ul ul { display:block; z-index:9999; width:60px; visibility: visible;}
.main-menu ul ul li a { display:block; width:60px; z-index:9999; visibility: visible;}
.main-menu ul li:hover > ul { display:block; width:60px; visibility: visible; }

.menu-item-74 li:hover > ul {display:block; visibility: visible; width:140px;}

.menu li.current_page_item a {background-color:#400072;}

Would be great if someone could get back to me today.

Thanks! 🙂