Reply To: Header size and Logo size on Header

You can add padding/space to the sides of each menu item by changing the padding on line 1292 –

.genesis-nav-menu a {
	color: #fff;
	display: block;
	font-size: 15px;
	font-weight: 300;
	letter-spacing: 2px;
	padding: 75px 17px;
	padding-top: 113px;
	padding-bottom: 23px;
	padding-left: 11px;
	text-transform: uppercase;
}

I would remove some of the padding code that you have above and instead add it like this –

padding: 113px 17px 23px 11px;

The padding works in this order – Top - Right - Bottom - Left So to add more space on the sides, change the 17px and the 11px (right and left). I would make them both the same so everything can be even.