Index: src/wp-admin/css/themes.css
===================================================================
--- src/wp-admin/css/themes.css	(revision 37281)
+++ src/wp-admin/css/themes.css	(working copy)
@@ -1329,17 +1329,16 @@
 .theme-install-overlay .close-full-overlay,
 .theme-install-overlay .previous-theme,
 .theme-install-overlay .next-theme {
-	display: block;
+	padding: 0;
 	position: relative;
 	float: left;
-	width: 45px;
+	width: 48px;
 	height: 45px;
-	padding-right: 2px;
-	background: #eee;
+	background: transparent;
+	border: 0;
 	border-right: 1px solid #ddd;
 	color: #444;
 	cursor: pointer;
-	text-decoration: none;
 	-webkit-transition: color .1s ease-in-out, background .1s ease-in-out;
 	transition: color .1s ease-in-out, background .1s ease-in-out;
 }
@@ -1362,8 +1361,7 @@
 	font: normal 22px/1 dashicons;
 	content: "\f335";
 	position: relative;
-	top: 7px;
-	left: 13px;
+	top: 2px;
 }
 
 .theme-install-overlay .previous-theme:before {
@@ -1370,8 +1368,8 @@
 	font: normal 20px/1 dashicons;
 	content: "\f341";
 	position: relative;
-	top: 6px;
-	left: 14px;
+	top: 2px;
+	left: 1px;
 }
 
 .theme-install-overlay .next-theme:before {
@@ -1378,8 +1376,7 @@
 	font: normal 20px/1 dashicons;
 	content: "\f345";
 	position: relative;
-	top: 6px;
-	left: 13px;
+	top: 2px;
 }
 
 .theme-install-overlay .previous-theme.disabled,
Index: src/wp-admin/js/theme.js
===================================================================
--- src/wp-admin/js/theme.js	(revision 37281)
+++ src/wp-admin/js/theme.js	(working copy)
@@ -572,12 +572,12 @@
 
 		// Disable previous at the zero position
 		if ( 0 === this.model.collection.indexOf( current ) ) {
-			$themeInstaller.find( '.previous-theme' ).addClass( 'disabled' );
+			$themeInstaller.find( '.previous-theme' ).addClass( 'disabled' ).attr({ 'tabindex': '-1', 'aria-hidden': 'true' });
 		}
 
 		// Disable next if the next model is undefined
 		if ( _.isUndefined( this.model.collection.at( this.model.collection.indexOf( current ) + 1 ) ) ) {
-			$themeInstaller.find( '.next-theme' ).addClass( 'disabled' );
+			$themeInstaller.find( '.next-theme' ).addClass( 'disabled' ).attr({ 'tabindex': '-1', 'aria-hidden': 'true' });
 		}
 	}
 });
@@ -697,10 +697,10 @@
 
 		// Disable Left/Right when at the start or end of the collection
 		if ( this.model.cid === this.model.collection.at(0).cid ) {
-			this.$el.find( '.left' ).addClass( 'disabled' );
+			this.$el.find( '.left' ).addClass( 'disabled' ).attr({ 'tabindex': '-1', 'aria-hidden': 'true' });
 		}
 		if ( this.model.cid === this.model.collection.at( this.model.collection.length - 1 ).cid ) {
-			this.$el.find( '.right' ).addClass( 'disabled' );
+			this.$el.find( '.right' ).addClass( 'disabled' ).attr({ 'tabindex': '-1', 'aria-hidden': 'true' });
 		}
 	},
 
Index: src/wp-admin/theme-install.php
===================================================================
--- src/wp-admin/theme-install.php	(revision 37281)
+++ src/wp-admin/theme-install.php	(working copy)
@@ -251,11 +251,11 @@
 <script id="tmpl-theme-preview" type="text/template">
 	<div class="wp-full-overlay-sidebar">
 		<div class="wp-full-overlay-header">
-			<a href="#" class="close-full-overlay"><span class="screen-reader-text"><?php _e( 'Close' ); ?></span></a>
-			<a href="#" class="previous-theme"><span class="screen-reader-text"><?php _ex( 'Previous', 'Button label for a theme' ); ?></span></a>
-			<a href="#" class="next-theme"><span class="screen-reader-text"><?php _ex( 'Next', 'Button label for a theme' ); ?></span></a>
+			<button type="button" class="close-full-overlay"><span class="screen-reader-text"><?php _e( 'Close' ); ?></span></button>
+			<button type="button" class="previous-theme"><span class="screen-reader-text"><?php _ex( 'Previous', 'Button label for a theme' ); ?></span></button>
+			<button type="button" class="next-theme"><span class="screen-reader-text"><?php _ex( 'Next', 'Button label for a theme' ); ?></span></button>
 		<# if ( data.installed ) { #>
-			<a href="#" class="button button-primary theme-install disabled"><?php _ex( 'Installed', 'theme' ); ?></a>
+			<span class="button button-primary theme-install disabled"><?php _ex( 'Installed', 'theme' ); ?></span>
 		<# } else { #>
 			<a href="{{ data.install_url }}" class="button button-primary theme-install"><?php _e( 'Install' ); ?></a>
 		<# } #>
Index: src/wp-admin/themes.php
===================================================================
--- src/wp-admin/themes.php	(revision 37281)
+++ src/wp-admin/themes.php	(working copy)
@@ -404,9 +404,9 @@
 	<div class="theme-backdrop"></div>
 	<div class="theme-wrap wp-clearfix">
 		<div class="theme-header">
-			<button class="left dashicons dashicons-no"><span class="screen-reader-text"><?php _e( 'Show previous theme' ); ?></span></button>
-			<button class="right dashicons dashicons-no"><span class="screen-reader-text"><?php _e( 'Show next theme' ); ?></span></button>
-			<button class="close dashicons dashicons-no"><span class="screen-reader-text"><?php _e( 'Close details dialog' ); ?></span></button>
+			<button type="button" class="left dashicons dashicons-no"><span class="screen-reader-text"><?php _e( 'Show previous theme' ); ?></span></button>
+			<button type="button" class="right dashicons dashicons-no"><span class="screen-reader-text"><?php _e( 'Show next theme' ); ?></span></button>
+			<button type="button" class="close dashicons dashicons-no"><span class="screen-reader-text"><?php _e( 'Close details dialog' ); ?></span></button>
 		</div>
 		<div class="theme-about wp-clearfix">
 			<div class="theme-screenshots">
