diff --git a/src/wp-admin/css/list-tables.css b/src/wp-admin/css/list-tables.css
index ab6581fd30..fa98d9972d 100644
--- a/src/wp-admin/css/list-tables.css
+++ b/src/wp-admin/css/list-tables.css
@@ -974,14 +974,6 @@ tr.inline-edit-row td,
 	line-height: 2.5;
 }
 
-.inline-edit-row fieldset .inline-edit-group:after {
-	content: ".";
-	display: block;
-	height: 0;
-	clear: both;
-	visibility: hidden;
-}
-
 .inline-edit-row p.submit {
 	clear: both;
 	padding: 0.5em;
diff --git a/src/wp-admin/css/nav-menus.css b/src/wp-admin/css/nav-menus.css
index 8dd0a15884..ccca9fc3c8 100644
--- a/src/wp-admin/css/nav-menus.css
+++ b/src/wp-admin/css/nav-menus.css
@@ -747,23 +747,6 @@ body.menu-max-depth-11 { min-width: 1280px !important; }
 	margin-left: -4px;
 }
 
-/* Clearfix */
-#menu-item-name-wrap:after,
-#menu-item-url-wrap:after,
-#menu-name-label:after,
-#menu-settings-column .inside:after,
-#nav-menus-frame:after,
-.nav-menus-php #post-body-content:after,
-.nav-menus-php .button-controls:after,
-.nav-menus-php .major-publishing-actions:after,
-.nav-menus-php .menu-item-settings:after {
-	clear: both;
-	content: ".";
-	display: block;
-	height: 0;
-	visibility: hidden;
-}
-
 #nav-menus-frame,
 .button-controls,
 #menu-item-url-wrap,
diff --git a/src/wp-admin/css/themes.css b/src/wp-admin/css/themes.css
index 183fd8f406..58ce25aa2c 100644
--- a/src/wp-admin/css/themes.css
+++ b/src/wp-admin/css/themes.css
@@ -524,14 +524,6 @@
 	-webkit-overflow-scrolling: touch;
 }
 
-.theme-overlay .theme-wrap:after {
-	content: ".";
-	display: block;
-	height: 0;
-	clear: both;
-	visibility: hidden;
-}
-
 body.folded .theme-overlay .theme-wrap {
 	left: 70px;
 }
@@ -545,13 +537,6 @@ body.folded .theme-overlay .theme-wrap {
 	overflow: auto;
 	padding: 2% 4%;
 }
-.theme-overlay .theme-about:after {
-	content: ".";
-	display: block;
-	height: 0;
-	clear: both;
-	visibility: hidden;
-}
 
 .theme-overlay .theme-actions {
 	position: absolute;
diff --git a/src/wp-admin/css/widgets.css b/src/wp-admin/css/widgets.css
index d358018686..72c3bdd299 100644
--- a/src/wp-admin/css/widgets.css
+++ b/src/wp-admin/css/widgets.css
@@ -230,14 +230,6 @@ div#widgets-left .inactive-sidebar .widgets-sortables {
 
 /* Widgets Right */
 
-div#widgets-right:after {
-	content: ".";
-	display: block;
-	height: 0;
-	clear: both;
-	visibility: hidden;
-}
-
 div#widgets-right .sidebars-column-1,
 div#widgets-right .sidebars-column-2 {
 	max-width: 450px;
diff --git a/src/wp-admin/customize.php b/src/wp-admin/customize.php
index 1195e9ad5d..1bc702bfae 100644
--- a/src/wp-admin/customize.php
+++ b/src/wp-admin/customize.php
@@ -127,7 +127,7 @@ do_action( 'customize_controls_print_scripts' );
 			</a>
 		</div>
 
-		<div id="widgets-right"><!-- For Widget Customizer, many widgets try to look for instances under div#widgets-right, so we have to add that ID to a container div in the Customizer for compat -->
+		<div id="widgets-right" class="wp-clearfix"><!-- For Widget Customizer, many widgets try to look for instances under div#widgets-right, so we have to add that ID to a container div in the Customizer for compat -->
 		<div class="wp-full-overlay-sidebar-content" tabindex="-1">
 			<div id="customize-info" class="accordion-section customize-info">
 				<div class="accordion-section-title">
diff --git a/src/wp-admin/includes/class-walker-nav-menu-edit.php b/src/wp-admin/includes/class-walker-nav-menu-edit.php
index b54f5127f0..b13e9d8465 100644
--- a/src/wp-admin/includes/class-walker-nav-menu-edit.php
+++ b/src/wp-admin/includes/class-walker-nav-menu-edit.php
@@ -150,7 +150,7 @@ class Walker_Nav_Menu_Edit extends Walker_Nav_Menu {
 				</div>
 			</div>
 
-			<div class="menu-item-settings" id="menu-item-settings-<?php echo $item_id; ?>">
+			<div class="menu-item-settings wp-clearfix" id="menu-item-settings-<?php echo $item_id; ?>">
 				<?php if ( 'custom' == $item->type ) : ?>
 					<p class="field-url description description-wide">
 						<label for="edit-menu-item-url-<?php echo $item_id; ?>">
diff --git a/src/wp-admin/includes/class-wp-posts-list-table.php b/src/wp-admin/includes/class-wp-posts-list-table.php
index 5422e5eefe..227cc4ab7d 100644
--- a/src/wp-admin/includes/class-wp-posts-list-table.php
+++ b/src/wp-admin/includes/class-wp-posts-list-table.php
@@ -1405,7 +1405,7 @@ class WP_Posts_List_Table extends WP_List_Table {
 	if ( !$bulk && $can_publish ) :
 	?>
 
-			<div class="inline-edit-group">
+			<div class="inline-edit-group wp-clearfix">
 				<label class="alignleft">
 					<span class="title"><?php _e( 'Password' ); ?></span>
 					<span class="input-text-wrap"><input type="text" name="post_password" class="inline-edit-password-input" value="" /></span>
@@ -1537,7 +1537,7 @@ class WP_Posts_List_Table extends WP_List_Table {
 	<?php if ( post_type_supports( $screen->post_type, 'comments' ) || post_type_supports( $screen->post_type, 'trackbacks' ) ) :
 		if ( $bulk ) : ?>
 
-			<div class="inline-edit-group">
+			<div class="inline-edit-group wp-clearfix">
 		<?php if ( post_type_supports( $screen->post_type, 'comments' ) ) : ?>
 			<label class="alignleft">
 				<span class="title"><?php _e( 'Comments' ); ?></span>
@@ -1561,7 +1561,7 @@ class WP_Posts_List_Table extends WP_List_Table {
 
 	<?php else : // $bulk ?>
 
-			<div class="inline-edit-group">
+			<div class="inline-edit-group wp-clearfix">
 			<?php if ( post_type_supports( $screen->post_type, 'comments' ) ) : ?>
 				<label class="alignleft">
 					<input type="checkbox" name="comment_status" value="open" />
@@ -1578,7 +1578,7 @@ class WP_Posts_List_Table extends WP_List_Table {
 	<?php endif; // $bulk
 	endif; // post_type_supports comments or pings ?>
 
-			<div class="inline-edit-group">
+			<div class="inline-edit-group wp-clearfix">
 				<label class="inline-edit-status alignleft">
 					<span class="title"><?php _e( 'Status' ); ?></span>
 					<select name="_status">
diff --git a/src/wp-admin/includes/nav-menu.php b/src/wp-admin/includes/nav-menu.php
index cb94fe2dc7..53eaec0218 100644
--- a/src/wp-admin/includes/nav-menu.php
+++ b/src/wp-admin/includes/nav-menu.php
@@ -263,17 +263,17 @@ function wp_nav_menu_item_link_meta_box() {
 	?>
 	<div class="customlinkdiv" id="customlinkdiv">
 		<input type="hidden" value="custom" name="menu-item[<?php echo $_nav_menu_placeholder; ?>][menu-item-type]" />
-		<p id="menu-item-url-wrap">
+		<p id="menu-item-url-wrap" class="wp-clearfix">
 			<label class="howto" for="custom-menu-item-url"><?php _e( 'URL' ); ?></label>
 			<input id="custom-menu-item-url" name="menu-item[<?php echo $_nav_menu_placeholder; ?>][menu-item-url]" type="text" class="code menu-item-textbox" value="http://" />
 		</p>
 
-		<p id="menu-item-name-wrap">
+		<p id="menu-item-name-wrap" class="wp-clearfix">
 			<label class="howto" for="custom-menu-item-name"><?php _e( 'Link Text' ); ?></label>
 			<input id="custom-menu-item-name" name="menu-item[<?php echo $_nav_menu_placeholder; ?>][menu-item-title]" type="text" class="regular-text menu-item-textbox" />
 		</p>
 
-		<p class="button-controls">
+		<p class="button-controls wp-clearfix">
 			<span class="add-to-menu">
 				<input type="submit"<?php wp_nav_menu_disabled_check( $nav_menu_selected_id ); ?> class="button-secondary submit-add-to-menu right" value="<?php esc_attr_e('Add to Menu'); ?>" name="add-custom-menu-item" id="submit-customlinkdiv" />
 				<span class="spinner"></span>
@@ -540,7 +540,7 @@ function wp_nav_menu_item_post_type_meta_box( $object, $post_type ) {
 			<?php endif; ?>
 		</div><!-- /.tabs-panel -->
 
-		<p class="button-controls">
+		<p class="button-controls wp-clearfix">
 			<span class="list-controls">
 				<a href="<?php
 					echo esc_url( add_query_arg(
@@ -731,7 +731,7 @@ function wp_nav_menu_item_taxonomy_meta_box( $object, $taxonomy ) {
 			</ul>
 		</div><!-- /.tabs-panel -->
 
-		<p class="button-controls">
+		<p class="button-controls wp-clearfix">
 			<span class="list-controls">
 				<a href="<?php
 					echo esc_url(add_query_arg(
diff --git a/src/wp-admin/includes/theme.php b/src/wp-admin/includes/theme.php
index c7a8ce5768..c3318af8c9 100644
--- a/src/wp-admin/includes/theme.php
+++ b/src/wp-admin/includes/theme.php
@@ -588,13 +588,13 @@ function customize_themes_print_templates() {
 	?>
 	<script type="text/html" id="tmpl-customize-themes-details-view">
 		<div class="theme-backdrop"></div>
-		<div class="theme-wrap">
+		<div class="theme-wrap wp-clearfix">
 			<div class="theme-header">
 				<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">
+			<div class="theme-about wp-clearfix">
 				<div class="theme-screenshots">
 				<# if ( data.screenshot[0] ) { #>
 					<div class="screenshot"><img src="{{ data.screenshot[0] }}" alt="" /></div>
diff --git a/src/wp-admin/nav-menus.php b/src/wp-admin/nav-menus.php
index 30aece33f4..8f17e03031 100644
--- a/src/wp-admin/nav-menus.php
+++ b/src/wp-admin/nav-menus.php
@@ -647,7 +647,7 @@ require_once( ABSPATH . 'wp-admin/admin-header.php' );
 				<?php } // foreach ?>
 				</tbody>
 			</table>
-			<p class="button-controls"><?php submit_button( __( 'Save Changes' ), 'primary left', 'nav-menu-locations', false ); ?></p>
+			<p class="button-controls wp-clearfix"><?php submit_button( __( 'Save Changes' ), 'primary left', 'nav-menu-locations', false ); ?></p>
 			<?php wp_nonce_field( 'save-menu-locations' ); ?>
 			<input type="hidden" name="menu" id="nav-menu-meta-object-id" value="<?php echo esc_attr( $nav_menu_selected_id ); ?>" />
 		</form>
@@ -714,7 +714,7 @@ require_once( ABSPATH . 'wp-admin/admin-header.php' );
 		</form>
 	<?php endif; ?>
 	</div><!-- /manage-menus -->
-	<div id="nav-menus-frame">
+	<div id="nav-menus-frame" class="wp-clearfix">
 	<div id="menu-settings-column" class="metabox-holder<?php if ( isset( $_GET['menu'] ) && '0' == $_GET['menu'] ) { echo ' metabox-holder-disabled'; } ?>">
 
 		<div class="clear"></div>
@@ -748,7 +748,7 @@ require_once( ABSPATH . 'wp-admin/admin-header.php' );
  					<input type="hidden" name="action" value="update" />
 					<input type="hidden" name="menu" id="menu" value="<?php echo esc_attr( $nav_menu_selected_id ); ?>" />
 					<div id="nav-menu-header">
-						<div class="major-publishing-actions">
+						<div class="major-publishing-actions wp-clearfix">
 							<label class="menu-name-label" for="menu-name"><?php _e( 'Menu Name' ); ?></label>
 							<input name="menu-name" id="menu-name" type="text" class="menu-name regular-text menu-item-textbox" <?php echo $menu_name_val . $menu_name_aria_desc; ?> />
 							<div class="publishing-action">
@@ -757,7 +757,7 @@ require_once( ABSPATH . 'wp-admin/admin-header.php' );
 						</div><!-- END .major-publishing-actions -->
 					</div><!-- END .nav-menu-header -->
 					<div id="post-body">
-						<div id="post-body-content">
+						<div id="post-body-content" class="wp-clearfix">
 							<?php if ( ! $add_new_screen ) : ?>
 							<h3><?php _e( 'Menu Structure' ); ?></h3>
 							<?php $starter_copy = ( $one_theme_location_no_menus ) ? __( 'Edit your default menu by adding or removing items. Drag each item into the order you prefer. Click Create Menu to save your changes.' ) : __( 'Drag each item into the order you prefer. Click the arrow on the right of the item to reveal additional configuration options.' ); ?>
@@ -822,7 +822,7 @@ require_once( ABSPATH . 'wp-admin/admin-header.php' );
 						</div><!-- /#post-body-content -->
 					</div><!-- /#post-body -->
 					<div id="nav-menu-footer">
-						<div class="major-publishing-actions">
+						<div class="major-publishing-actions wp-clearfix">
 							<?php if ( 0 != $menu_count && ! $add_new_screen ) : ?>
 							<span class="delete-action">
 								<a class="submitdelete deletion menu-delete" href="<?php echo esc_url( wp_nonce_url( add_query_arg( array( 'action' => 'delete', 'menu' => $nav_menu_selected_id ), admin_url( 'nav-menus.php' ) ), 'delete-nav_menu-' . $nav_menu_selected_id) ); ?>"><?php _e('Delete Menu'); ?></a>
diff --git a/src/wp-admin/themes.php b/src/wp-admin/themes.php
index 2724755df5..d229d9261d 100644
--- a/src/wp-admin/themes.php
+++ b/src/wp-admin/themes.php
@@ -402,13 +402,13 @@ $can_install = current_user_can( 'install_themes' );
 
 <script id="tmpl-theme-single" type="text/template">
 	<div class="theme-backdrop"></div>
-	<div class="theme-wrap">
+	<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>
 		</div>
-		<div class="theme-about">
+		<div class="theme-about wp-clearfix">
 			<div class="theme-screenshots">
 			<# if ( data.screenshot[0] ) { #>
 				<div class="screenshot"><img src="{{ data.screenshot[0] }}" alt="" /></div>
diff --git a/src/wp-admin/widgets.php b/src/wp-admin/widgets.php
index 4d23127fae..91d611cd1d 100644
--- a/src/wp-admin/widgets.php
+++ b/src/wp-admin/widgets.php
@@ -455,12 +455,12 @@ $sidebars_count = count( $theme_sidebars );
 if ( $sidebars_count > 1 ) {
 	$split = ceil( $sidebars_count / 2 );
 } else {
-	$single_sidebar_class = ' class="single-sidebar"';
+	$single_sidebar_class = ' single-sidebar';
 }
 
 ?>
 <div class="widget-liquid-right">
-<div id="widgets-right"<?php echo $single_sidebar_class; ?>>
+<div id="widgets-right" class="wp-clearfix<?php echo $single_sidebar_class; ?>">
 <div class="sidebars-column-1">
 <?php
 
diff --git a/src/wp-includes/class-wp-customize-nav-menus.php b/src/wp-includes/class-wp-customize-nav-menus.php
index 809eace303..5453c175a8 100644
--- a/src/wp-includes/class-wp-customize-nav-menus.php
+++ b/src/wp-includes/class-wp-customize-nav-menus.php
@@ -759,11 +759,11 @@ final class WP_Customize_Nav_Menus {
 				</h4>
 				<div class="accordion-section-content customlinkdiv">
 					<input type="hidden" value="custom" id="custom-menu-item-type" name="menu-item[-1][menu-item-type]" />
-					<p id="menu-item-url-wrap">
+					<p id="menu-item-url-wrap" class="wp-clearfix">
 						<label class="howto" for="custom-menu-item-url"><?php _e( 'URL' ); ?></label>
 						<input id="custom-menu-item-url" name="menu-item[-1][menu-item-url]" type="text" class="code menu-item-textbox" value="http://">
 					</p>
-					<p id="menu-item-name-wrap">
+					<p id="menu-item-name-wrap" class="wp-clearfix">
 						<label class="howto" for="custom-menu-item-name"><?php _e( 'Link Text' ); ?></label>
 						<input id="custom-menu-item-name" name="menu-item[-1][menu-item-title]" type="text" class="regular-text menu-item-textbox">
 					</p>