Color schemes: Add new modern color scheme option.

This PR adds a new color scheme option, which uses a high luminosity blue spot color, almost-black menu, and pure white for menu items. 
This helps increase contrast, and bring more consistency with some of the higher contrast colors used in the block editor.

Props joen, ibdz, shaunandrews.
Fixes #50504.


git-svn-id: https://develop.svn.wordpress.org/trunk@48277 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/css/colors/modern/colors.scss

@@ -0,0 +1,14 @@
+$base-color: #1e1e1e;
+$highlight-color: #3858e9;
+$menu-submenu-focus-text: #33f078;
+$notification-color: $highlight-color;
+
+$link: $highlight-color;
+$link-focus: darken($highlight-color, 10%);
+
+
+@import "../_admin.scss";
+
+#adminmenu .wp-submenu, #adminmenu .wp-has-current-submenu .wp-submenu, #adminmenu .wp-has-current-submenu.opensub .wp-submenu, .folded #adminmenu .wp-has-current-submenu .wp-submenu, #adminmenu a.wp-has-current-submenu:focus + .wp-submenu {
+	padding-bottom: 12px;
+}

src/wp-admin/includes/misc.php

@@ -934,6 +934,7 @@ function admin_color_scheme_picker( $user_id ) {
 				array(
 					'fresh' => '',
 					'light' => '',
+					'modern' => '',
 				),
 				$_wp_admin_css_colors
 			)

src/wp-includes/general-template.php

@@ -4366,6 +4366,18 @@ function register_admin_color_schemes() {
 		)
 	);
 
+	wp_admin_css_color(
+		'modern',
+		_x( 'Modern', 'admin color scheme' ),
+		admin_url( "css/colors/modern/colors$suffix.css" ),
+		array( '#1e1e1e', '#3858e9', '#e26f56' ),
+		array(
+			'base'    => '#1e1e1e',
+			'focus'   => '#3858e9',
+			'current' => '#e26f56',
+		)
+	);
+
 	wp_admin_css_color(
 		'blue',
 		_x( 'Blue', 'admin color scheme' ),