Index: src/wp-admin/css/common.css
===================================================================
--- src/wp-admin/css/common.css	(revision 34274)
+++ src/wp-admin/css/common.css	(working copy)
@@ -1525,10 +1525,12 @@
 	background-position: bottom left;
 }
 
-#screen-options-wrap h5,
+#screen-options-wrap legend,
 #contextual-help-wrap h5 {
-	margin: 8px 0;
+	margin: 0;
+	padding: 8px 0;
 	font-size: 13px;
+	font-weight: 600;
 }
 
 .metabox-prefs label {
@@ -1537,6 +1539,12 @@
 	line-height: 30px;
 }
 
+#number-of-columns {
+	display: inline-block;
+	vertical-align: middle;
+	line-height: 30px;
+}
+
 .metabox-prefs label input[type=checkbox] {
 	margin-top: -4px;
 	margin-right: 6px;
Index: src/wp-admin/css/customize-nav-menus.css
===================================================================
--- src/wp-admin/css/customize-nav-menus.css	(revision 34274)
+++ src/wp-admin/css/customize-nav-menus.css	(working copy)
@@ -349,7 +349,7 @@
 	display: none;
 	background: #fff;
 	border-top: 1px solid #ddd;
-	padding: 4px 15px 0;
+	padding: 4px 15px 15px;
 }
 
 .wp-customizer .metabox-prefs label {
Index: src/wp-admin/includes/class-wp-screen.php
===================================================================
--- src/wp-admin/includes/class-wp-screen.php	(revision 34274)
+++ src/wp-admin/includes/class-wp-screen.php	(working copy)
@@ -907,7 +907,8 @@
 		<?php endif; ?>
 		<form id="adv-settings" method="post">
 		<?php if ( isset( $wp_meta_boxes[ $this->id ] ) || $this->get_option( 'per_page' ) || ( $columns && empty( $columns['_title'] ) ) ) : ?>
-			<h5><?php _e( 'Show on screen' ); ?></h5>
+			<fieldset>
+				<legend><?php _e( 'Show on screen' ); ?></legend>
 		<?php
 		endif;
 
@@ -930,12 +931,12 @@
 						echo _x( 'Welcome', 'Welcome panel' ) . "</label>\n";
 					}
 				?>
-				<br class="clear" />
 			</div>
 			<?php endif;
 			if ( $columns ) :
 				if ( ! empty( $columns['_title'] ) ) : ?>
-			<h5><?php echo $columns['_title']; ?></h5>
+			<fieldset>
+				<legend><?php echo $columns['_title']; ?></legend>
 			<?php endif; ?>
 			<div class="metabox-prefs">
 				<?php
@@ -956,10 +957,15 @@
 					echo "$title</label>\n";
 				}
 				?>
-				<br class="clear" />
 			</div>
+			<?php if ( ! empty( $columns['_title'] ) ) : ?>
+			</fieldset>
+			<?php endif; ?>
 		<?php endif;
 
+		if ( isset( $wp_meta_boxes[ $this->id ] ) || $this->get_option( 'per_page' ) || ( $columns && empty( $columns['_title'] ) ) ) : ?>
+			</fieldset>
+		<?php endif;
 		$this->render_screen_layout();
 		$this->render_per_page_options();
 		echo $this->_screen_settings;
@@ -985,19 +991,18 @@
 		$num = $this->get_option( 'layout_columns', 'max' );
 
 		?>
-		<h5 class="screen-layout"><?php _e('Screen Layout'); ?></h5>
-		<div class='columns-prefs'><?php
-			_e('Number of Columns:');
-			for ( $i = 1; $i <= $num; ++$i ):
-				?>
+		<fieldset>
+		<legend class="screen-layout"><?php _e( 'Screen Layout' ); ?></legend>
+		<div class='columns-prefs'>
+			<span id='number-of-columns'><?php _e( 'Number of Columns:' ); ?></span>
+			<?php for ( $i = 1; $i <= $num; ++$i ): ?>
 				<label class="columns-prefs-<?php echo $i; ?>">
-					<input type='radio' name='screen_columns' value='<?php echo esc_attr( $i ); ?>'
-						<?php checked( $screen_layout_columns, $i ); ?> />
+					<input type="radio" name="screen_columns" aria-describedby="number-of-columns" value="<?php echo esc_attr( $i ); ?>" <?php checked( $screen_layout_columns, $i ); ?> />
 					<?php echo esc_html( $i ); ?>
 				</label>
-				<?php
-			endfor; ?>
+			<?php endfor; ?>
 		</div>
+		</fieldset>
 		<?php
 	}