You can remove that first line in your new css: (it's not needed)
@media screen and (min-width: 600px){make sure and get that final bracket as well.
The hovers are changing in the menu for me just now, too. Maybe you fixed that?
The spacing between menu items is the margin here: (40px to the right)
.main-navigation li {
margin: 0 40px 0 0;
}