Genesis accessibility CSS for quick reference along with PHP code to add theme support for HTML5 markup, mobile viewport, and accessibility features in child themes.

genesis_accessible_styles.css

/********** Screen Reader Text starts about line 482 ************/

th {
	font-weight: 400;
}

/* ## Screen Reader Text
--------------------------------------------- */

.screen-reader-text,
.screen-reader-text span,
.screen-reader-shortcut {
	position: absolute !important;
	clip: rect(0, 0, 0, 0);
	height: 1px;
	width: 1px;
	border: 0;
	overflow: hidden;
}

.screen-reader-text:focus,
.screen-reader-shortcut:focus,
.genesis-nav-menu .search input[type="submit"]:focus,
.widget_search input[type="submit"]:focus  {
	clip: auto !important;
	height: auto;
	width: auto;
	display: block;
	font-size: 1em;
	font-weight: bold;
	padding: 15px 23px 14px;
	color: #333;
	background: #fff;
	z-index: 100000; /* Above WP toolbar. */
	text-decoration: none;
	box-shadow: 0 0 2px 2px rgba(0,0,0,.6);
}

.more-link {
    position: relative;
}


/* # Structure and Layout
---------------------------------------------------------------------------------------------------- */

/********** Break to about line 933 ************/

/* ## Jetpack
--------------------------------------------- */

#wpstats {
	display: none;
}


/* # Skip Links
---------------------------------------------------------------------------------------------------- */
.genesis-skip-link {
	margin: 0;
}

.genesis-skip-link li {
	height: 0;
	width: 0;
	list-style: none;
}

/* Display outline on focus */
:focus {
	color: #333;
	outline: #ccc solid 1px;
}


/* # Site Header
---------------------------------------------------------------------------------------------------- */


/********** Break to about line 1119 ************/

.genesis-nav-menu > .search {
	padding: 10px 0 0;
}

/* ## Accessible Menu
--------------------------------------------- */

.menu .menu-item:focus {
	position: static;
}

.menu .menu-item > a:focus + ul.sub-menu,
.menu .menu-item.sfHover > ul.sub-menu {
	left: auto;
	opacity: 1;
}

/* ## Site Header Navigation
--------------------------------------------- */

html5-responsive-accessibility.php

<?php

/* Enable HTML5 markup, header responsive viewport meta tag, and accessiblity features. 
 * Hooking it into after_theme_setup allows them to work outside functions.php file.
 */

// Add HTML5, responsive, and accessibility theme support
add_action( 'after_setup_theme', 'wsm_theme_support' );

function wsm_theme_support() {
	
	// Add HTML5 markup structure
	add_theme_support( 'html5', array(
			'comment-list',
			'comment-form',
			'search-form',
			'gallery',
			'caption',
		) );

	// Add viewport meta tag for mobile browsers
	add_theme_support( 'genesis-responsive-viewport' );

	// Add accessibility support
	add_theme_support( 'genesis-accessibility', array(
			'404-page',
			'drop-down-menu',
			'headings',
			'rems',
			'search-form',
			'skip-links',
		) );

}