diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index f98df80..b983ddf 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -211,32 +211,28 @@ function _drupal_theme_initialize($theme, $base_theme = array()) {
   drupal_render($css);
 
   // Do basically the same as the above for scripts
-  $final_scripts = array();
+  $final_libraries = array();
 
   // Grab scripts from base theme
   foreach ($base_theme as $base) {
-    if (!empty($base->scripts)) {
-      foreach ($base->scripts as $name => $script) {
-        $final_scripts[$name] = $script;
+    if (!empty($base->libraries)) {
+      foreach ($base->libraries as $library) {
+        $final_libraries[] = $library;
       }
     }
   }
 
   // Add scripts used by this theme.
-  if (!empty($theme->scripts)) {
-    foreach ($theme->scripts as $name => $script) {
-      $final_scripts[$name] = $script;
+  if (!empty($theme->libraries)) {
+    foreach ($theme->libraries as $library) {
+      $final_libraries[] = $library;
     }
   }
 
   // Add scripts used by this theme.
   $js = array();
-  foreach ($final_scripts as $script) {
-    $js['#attached']['js'][] = array(
-      'data' => $script,
-      'group' => JS_THEME,
-      'every_page' => TRUE,
-    );
+  foreach ($final_libraries as $library) {
+    $js['#attached']['library'][] = $library;
   }
   drupal_render($js);
 
diff --git a/core/lib/Drupal/Core/Extension/ThemeHandler.php b/core/lib/Drupal/Core/Extension/ThemeHandler.php
index 35ab1d4..ba658c2 100644
--- a/core/lib/Drupal/Core/Extension/ThemeHandler.php
+++ b/core/lib/Drupal/Core/Extension/ThemeHandler.php
@@ -206,8 +206,8 @@ public function listInfo() {
             $theme->stylesheets[$media][$stylesheet] = $path;
           }
         }
-        foreach ($theme->info['scripts'] as $script => $path) {
-          $theme->scripts[$script] = $path;
+        foreach ($theme->info['libraries'] as $library => $name) {
+          $theme->libraries[$library] = $name;
         }
         if (isset($theme->info['engine'])) {
           $theme->engine = $theme->info['engine'];
@@ -265,7 +265,7 @@ public function rebuildThemeData() {
       'screenshot' => 'screenshot.png',
       'php' => DRUPAL_MINIMUM_PHP,
       'stylesheets' => array(),
-      'scripts' => array(),
+      'libraries' => array(),
     );
 
     $sub_themes = array();
@@ -294,10 +294,9 @@ public function rebuildThemeData() {
         $theme->prefix = $engines[$engine]->getName();
       }
 
-      // Prefix stylesheets, scripts, and screenshot with theme path.
+      // Prefix stylesheets and screenshot with theme path.
       $path = $theme->getPath();
       $theme->info['stylesheets'] = $this->themeInfoPrefixPath($theme->info['stylesheets'], $path);
-      $theme->info['scripts'] = $this->themeInfoPrefixPath($theme->info['scripts'], $path);
       if (!empty($theme->info['screenshot'])) {
         $theme->info['screenshot'] = $path . '/' . $theme->info['screenshot'];
       }
@@ -338,7 +337,7 @@ public function rebuildThemeData() {
    *
    * This helper function is mainly used to prefix all array values of an
    * .info.yml file property with a single given path (to the module or theme);
-   * e.g., to prefix all values of the 'stylesheets' or 'scripts' properties
+   * e.g., to prefix all values of the 'stylesheets' properties
    * with the file path to the defining module/theme.
    *
    * @param array $info
diff --git a/core/themes/bartik/bartik.info.yml b/core/themes/bartik/bartik.info.yml
index 6851a12..a0fee0f 100644
--- a/core/themes/bartik/bartik.info.yml
+++ b/core/themes/bartik/bartik.info.yml
@@ -4,13 +4,8 @@ description: 'A flexible, recolorable theme with many regions and a responsive,
 package: Core
 version: VERSION
 core: 8.x
-stylesheets:
-  all:
-    - css/layout.css
-    - css/style.css
-    - css/colors.css
-  print:
-    - css/print.css
+libraries:
+  - bartik/base
 ckeditor_stylesheets:
   - css/ckeditor-iframe.css
 regions:
diff --git a/core/themes/bartik/bartik.libraries.yml b/core/themes/bartik/bartik.libraries.yml
index c864016..410c21c 100644
--- a/core/themes/bartik/bartik.libraries.yml
+++ b/core/themes/bartik/bartik.libraries.yml
@@ -1,3 +1,12 @@
+base:
+  version: VERSION
+  css:
+    theme:
+      css/layout.css: {}
+      css/style.css: {}
+      css/colors.css: {}
+      css/print.css: { media: print }
+
 maintenance_page:
   version: VERSION
   css: