Make Genesis Child Theme Header Menu Responsive - https://www.techmuzz.com/how-to/make-genesis-child-theme-header-menu-responsive/

functions.php

function custom_scripts_styles_mobile_responsive() {
	wp_enqueue_script( 'beautiful-responsive-menu', get_bloginfo( 'stylesheet_directory' ) . '/js/responsive-menu.js', array( 'jquery' ), '1.0.0' );
	wp_enqueue_style( 'dashicons' );
}
add_action( 'wp_enqueue_scripts', 'custom_scripts_styles_mobile_responsive' );

responsive-menu.js

jQuery(function( $ ){

	$("header .genesis-nav-menu, .nav-primary .genesis-nav-menu, .nav-secondary .genesis-nav-menu").addClass("responsive-menu").before('<div class="responsive-menu-icon"></div>');

	$(".responsive-menu-icon").click(function(){
		$(this).next("header .genesis-nav-menu, .nav-primary .genesis-nav-menu, .nav-secondary .genesis-nav-menu").slideToggle();
	});

	$(window).resize(function(){
		if(window.innerWidth > 768) {
			$("header .genesis-nav-menu, .nav-primary .genesis-nav-menu, .nav-secondary .genesis-nav-menu, nav .sub-menu").removeAttr("style");
			$(".responsive-menu > .menu-item").removeClass("menu-open");
		}
	});

	$(".responsive-menu > .menu-item").click(function(event){
		if (event.target !== this)
		return;
			$(this).find(".sub-menu:first").slideToggle(function() {
			$(this).parent().toggleClass("menu-open");
		});
	});

});

style.css

/* Responsive Menu
--------------------------------------------- */

.responsive-menu-icon {
	cursor: pointer;
	display: none;
	margin-bottom: -1px;
	text-align: center;
}

.responsive-menu-icon::before {
	content: "\f333";
	display: inline-block;
	font: normal 20px/1 'dashicons';
	margin: 0 auto;
	padding: 10px;
}
.nav-primary .responsive-menu-icon::before {
	color: #fff;
}

@media only screen and (max-width: 768px) {

	.genesis-nav-menu.responsive-menu > .menu-item > .sub-menu,
	.genesis-nav-menu.responsive-menu {
		display: none;
	}

	.genesis-nav-menu.responsive-menu .menu-item,
	.responsive-menu-icon {
		display: block;
	}

	.genesis-nav-menu.responsive-menu .menu-item {
		margin: 0;
	}

	.genesis-nav-menu.responsive-menu .menu-item:hover {
		position: static;
	}

	.genesis-nav-menu.responsive-menu .current-menu-item > a,
	.genesis-nav-menu.responsive-menu .sub-menu .current-menu-item > a:hover,
	.genesis-nav-menu.responsive-menu a,
	.genesis-nav-menu.responsive-menu a:hover {
		background: none;
		line-height: 1;
		padding: 16px 20px;
	}
	.nav-primary .genesis-nav-menu.responsive-menu .current-menu-item > a,
	.nav-primary .genesis-nav-menu.responsive-menu .sub-menu .current-menu-item > a:hover,
	.nav-primary .genesis-nav-menu.responsive-menu a,
	.nav-primary .genesis-nav-menu.responsive-menu a:hover {
		color: #fff;
	}

	.genesis-nav-menu.responsive-menu .menu-item-has-children {
		cursor: pointer;
	}

	.genesis-nav-menu.responsive-menu .menu-item-has-children > a {
		margin-right: 60px;
	}

	.genesis-nav-menu.responsive-menu > .menu-item-has-children:before {
		content: "\f347";
		float: right;
		font: normal 16px/1 'dashicons';
		height: 16px;
		padding: 16px 20px;
		right: 0;
		text-align: right;
		z-index: 9999;
	}
	.nav-primary .genesis-nav-menu.responsive-menu > .menu-item-has-children:before {
		color: #fff;
	}

	.genesis-nav-menu.responsive-menu .menu-open.menu-item-has-children:before {
		content: "\f343";
	}

	.genesis-nav-menu.responsive-menu .sub-menu {
		border: none;
		left: auto;
		opacity: 1;
		padding-left: 25px;
		position: relative;
		-moz-transition:    opacity .4s ease-in-out;
		-ms-transition:     opacity .4s ease-in-out;
		-o-transition:      opacity .4s ease-in-out;
		-webkit-transition: opacity .4s ease-in-out;
		transition:         opacity .4s ease-in-out;
		width: 100%;
		z-index: 99;
	}

	.genesis-nav-menu.responsive-menu .sub-menu .sub-menu {
		margin: 0;
	}

	.genesis-nav-menu.responsive-menu .sub-menu .current-menu-item > a:hover,
	.genesis-nav-menu.responsive-menu .sub-menu li a,
	.genesis-nav-menu.responsive-menu .sub-menu li a:hover {
		background: none;
		border: none;
		padding: 12px 20px;
		position: relative;
		width: 100%;
	}

}