Reply To: How to change width of primary navigation?

You added this on line 2029 in your css –

.nav-primary {
max-width: 750px;
}

That’s where the width limit is coming from. Remove that altogether first.

Then you’ll want to replace float: left; on line 2012 with display: inline-block; in order to center the entire nav –

.genesis-nav-menu .menu-item {
	display: inline-block;
	/* float: left; */
	list-style-type: none;
	margin: 0;
	padding: 0;
	text-align: left;
}