diff --git a/lib/block-supports/layout.php b/lib/block-supports/layout.php
index f70e1cae176dd4..350d158cd6e24f 100644
--- a/lib/block-supports/layout.php
+++ b/lib/block-supports/layout.php
@@ -45,16 +45,7 @@ function gutenberg_get_layout_definitions() {
 					),
 				),
 			),
-			// First/last child rules need to be after `> *` rule to take
-			// precedence when they have the same specificity.
 			'spacingStyles' => array(
-				array(
-					'selector' => ' > *',
-					'rules'    => array(
-						'margin-block-start' => null,
-						'margin-block-end'   => '0',
-					),
-				),
 				array(
 					'selector' => ' > :first-child',
 					'rules'    => array(
@@ -67,6 +58,13 @@ function gutenberg_get_layout_definitions() {
 						'margin-block-end' => '0',
 					),
 				),
+				array(
+					'selector' => ' > *',
+					'rules'    => array(
+						'margin-block-start' => null,
+						'margin-block-end'   => '0',
+					),
+				),
 			),
 		),
 		'constrained' => array(
@@ -112,16 +110,7 @@ function gutenberg_get_layout_definitions() {
 					),
 				),
 			),
-			// First/last child rules need to be after `> *` rule to take
-			// precedence when they have the same specificity.
 			'spacingStyles' => array(
-				array(
-					'selector' => ' > *',
-					'rules'    => array(
-						'margin-block-start' => null,
-						'margin-block-end'   => '0',
-					),
-				),
 				array(
 					'selector' => ' > :first-child',
 					'rules'    => array(
@@ -134,6 +123,13 @@ function gutenberg_get_layout_definitions() {
 						'margin-block-end' => '0',
 					),
 				),
+				array(
+					'selector' => ' > *',
+					'rules'    => array(
+						'margin-block-start' => null,
+						'margin-block-end'   => '0',
+					),
+				),
 			),
 		),
 		'flex'        => array(
diff --git a/lib/class-wp-theme-json-gutenberg.php b/lib/class-wp-theme-json-gutenberg.php
index 34c44efe3efd14..63e446be9c1c67 100644
--- a/lib/class-wp-theme-json-gutenberg.php
+++ b/lib/class-wp-theme-json-gutenberg.php
@@ -1724,7 +1724,7 @@ protected function get_layout_styles( $block_metadata, $types = array() ) {
 										$spacing_rule['selector']
 									);
 								} else {
-									$format          = static::ROOT_BLOCK_SELECTOR === $selector ? ':root :where(.%2$s %3$s)' : ':root :where(%1$s-%2$s %3$s)';
+									$format          = static::ROOT_BLOCK_SELECTOR === $selector ? ':root :where(.%2$s)%3$s' : ':root :where(%1$s-%2$s)%3$s';
 									$layout_selector = sprintf(
 										$format,
 										$selector,