Center Logo and Menu in Genesis 2.6 - https://amethystwebsitedesign.com/center-logo-and-menu-in-genesis-sample-2-6/

style-center-large-screens.css

/* Center logo and menu on only large screens. */
@media only screen and (min-width: 960px) {
	
	.wp-custom-logo .title-area,
	.wp-custom-logo .nav-primary {
		float: none;
	}

	.wp-custom-logo .title-area {
		margin: 0 auto;
		text-align: center;
	}
	
	.wp-custom-logo .nav-primary {
		text-align: center;
	}

	.wp-custom-logo .nav-primary .sub-menu {
		text-align: left;
	}
}

style-center-large-small-screens.css

/* Center logo and menu on large and small screens. */
.wp-custom-logo .title-area,
.wp-custom-logo .menu-toggle,
.wp-custom-logo .nav-primary {
	float: none;
}

.wp-custom-logo .title-area {
	margin: 0 auto;
	text-align: center;
}

@media only screen and (min-width: 960px) {
	.wp-custom-logo .nav-primary {
		text-align: center;
	}

	.wp-custom-logo .nav-primary .sub-menu {
		text-align: left;
	}
}

style-no-fixed-header.css

/* No fixed header. */
.site-header {
	position: static;
}