diff --git a/core/modules/system/css/components/animated-throbber.module.css b/core/modules/system/css/components/autocomplete-loading.module.css
similarity index 96%
rename from core/modules/system/css/components/animated-throbber.module.css
rename to core/modules/system/css/components/autocomplete-loading.module.css
index 1609f6f..40d3323 100644
--- a/core/modules/system/css/components/animated-throbber.module.css
+++ b/core/modules/system/css/components/autocomplete-loading.module.css
@@ -2,7 +2,7 @@
  * @file
  * Visual styles for animated throbber.
  *
- * @see autocomple.js
+ * @see autocomplete.js
  */
 
 .js input.form-autocomplete {
diff --git a/core/modules/system/css/components/breadcrumbs.theme.css b/core/modules/system/css/components/breadcrumb.theme.css
similarity index 100%
rename from core/modules/system/css/components/breadcrumbs.theme.css
rename to core/modules/system/css/components/breadcrumb.theme.css
diff --git a/core/modules/system/css/components/collapse-processed.theme.css b/core/modules/system/css/components/collapse-processed.theme.css
index 50a2003..896b637 100644
--- a/core/modules/system/css/components/collapse-processed.theme.css
+++ b/core/modules/system/css/components/collapse-processed.theme.css
@@ -1,6 +1,6 @@
 /**
  * @file
- * Visual styles for collapse processed.
+ * Visual styles for collapsible fieldsets.
  */
 
 .collapse-processed > summary {
diff --git a/core/modules/system/css/components/container-inline.theme.css b/core/modules/system/css/components/container-inline.theme.css
index 5ce4005..785e4de 100644
--- a/core/modules/system/css/components/container-inline.theme.css
+++ b/core/modules/system/css/components/container-inline.theme.css
@@ -1,6 +1,8 @@
 /**
+ * @file
  * Inline items.
  */
+
 .container-inline label:after,
 .container-inline .label:after {
   content: ':';
diff --git a/core/modules/system/css/components/details.module.css b/core/modules/system/css/components/details.module.css
index 71a4133..23ee3b4 100644
--- a/core/modules/system/css/components/details.module.css
+++ b/core/modules/system/css/components/details.module.css
@@ -1,4 +1,5 @@
 /**
+ * @file
  * Collapsible details.
  *
  * @see collapse.js
diff --git a/core/modules/system/css/components/details.theme.css b/core/modules/system/css/components/details.theme.css
index 793da94..641dd12 100644
--- a/core/modules/system/css/components/details.theme.css
+++ b/core/modules/system/css/components/details.theme.css
@@ -1,8 +1,9 @@
 /**
+ * @file
  * Collapsible details.
  *
  * @see collapse.js
- * @thanks http://nicolasgallagher.com/css-background-image-hacks/
+ * @see http://nicolasgallagher.com/css-background-image-hacks/
  */
 
 details {
diff --git a/core/modules/system/css/components/menu.theme.css b/core/modules/system/css/components/menu.theme.css
index 05f5b1a..6dd26eb 100644
--- a/core/modules/system/css/components/menu.theme.css
+++ b/core/modules/system/css/components/menu.theme.css
@@ -14,21 +14,21 @@ ul.menu {
   margin-right: 1em;
   text-align: right;
 }
-.menu .expanded {
+.menu-item--expanded {
   list-style-image: url(../../../../misc/menu-expanded.png);
   list-style-type: circle;
 }
-.menu .collapsed {
+.menu-item--collapsed {
   list-style-image: url(../../../../misc/menu-collapsed.png); /* LTR */
   list-style-type: disc;
 }
-[dir="rtl"] .menu .collapsed {
+[dir="rtl"] .menu-item--collapsed {
   list-style-image: url(../../../../misc/menu-collapsed-rtl.png);
 }
-ul.menu li {
+.menu-item {
   padding-top: 0.2em;
   margin: 0;
 }
-ul.menu a.active {
+ul.menu a.is-active {
   color: #000;
 }
diff --git a/core/modules/system/css/components/more-help.theme.css b/core/modules/system/css/components/more-help.theme.css
deleted file mode 100644
index 32bfb3e..0000000
--- a/core/modules/system/css/components/more-help.theme.css
+++ /dev/null
@@ -1,19 +0,0 @@
-/**
- * @file
- * More help link style.
- */
-
-.more-help-link {
-  text-align: right; /* LTR */
-}
-[dir="rtl"] .more-help-link {
-  text-align: left;
-}
-.more-help-link a {
-  background: url(../../../../misc/help.png) 0 50% no-repeat; /* LTR */
-  padding: 1px 0 1px 20px; /* LTR */
-}
-[dir="rtl"] .more-help-link a {
-  background-position: 100% 50%;
-  padding: 1px 20px 1px 0;
-}
diff --git a/core/modules/system/css/components/node.theme.css b/core/modules/system/css/components/node.theme.css
index 040e8db..6b7cd52 100644
--- a/core/modules/system/css/components/node.theme.css
+++ b/core/modules/system/css/components/node.theme.css
@@ -1,6 +1,6 @@
 /**
  * @file
- * Visual styles for node--unpublished.
+ * Visual styles for nodes.
  */
 
 .node--unpublished {
diff --git a/core/modules/system/css/components/pager.theme.css b/core/modules/system/css/components/pager.theme.css
index 5441db4..a9471fc 100644
--- a/core/modules/system/css/components/pager.theme.css
+++ b/core/modules/system/css/components/pager.theme.css
@@ -8,9 +8,7 @@
   text-align: center;
 }
 .pager__item {
-  background-image: none;
   display: inline;
-  list-style-type: none;
   padding: 0.5em;
 }
 .pager__item.is-active {
diff --git a/core/modules/system/css/components/reset-appearance.module.css b/core/modules/system/css/components/reset-appearance.module.css
index 28c71e9..847f269 100644
--- a/core/modules/system/css/components/reset-appearance.module.css
+++ b/core/modules/system/css/components/reset-appearance.module.css
@@ -1,7 +1,8 @@
 /*
  * @file
- * Utility class to remove browser styles, especially for <buttons> and so on.
+ * Utility class to remove browser styles, especially for button.
  */
+
 .reset-appearance {
   -webkit-appearance: none;
   -moz-appearance: none;
diff --git a/core/modules/system/css/components/sticky-header.css b/core/modules/system/css/components/sticky-header.module.css
similarity index 100%
rename from core/modules/system/css/components/sticky-header.css
rename to core/modules/system/css/components/sticky-header.module.css
diff --git a/core/modules/system/css/components/tabledrag.module.css b/core/modules/system/css/components/tabledrag.module.css
index eaea9b3..f4e21ff 100644
--- a/core/modules/system/css/components/tabledrag.module.css
+++ b/core/modules/system/css/components/tabledrag.module.css
@@ -1,6 +1,6 @@
 /**
  * @file
- * TableDrag behavior.
+ * Table drag behavior.
  *
  * @see tabledrag.js
  */
@@ -64,6 +64,12 @@ a.tabledrag-handle:focus .handle {
 .touch .draggable.drag a.tabledrag-handle .handle {
   background-position: 50% -32px;
 }
+.tabledrag-toggle-weight-wrapper {
+  text-align: right; /* LTR */
+}
+[dir="rtl"] .tabledrag-toggle-weight-wrapper {
+  text-align: left;
+}
 .indentation {
   float: left; /* LTR */
   height: 1.7em;
diff --git a/core/modules/system/css/components/table-select.theme.css b/core/modules/system/css/components/tableselect.theme.css
similarity index 83%
rename from core/modules/system/css/components/table-select.theme.css
rename to core/modules/system/css/components/tableselect.theme.css
index 882707a..864614e 100644
--- a/core/modules/system/css/components/table-select.theme.css
+++ b/core/modules/system/css/components/tableselect.theme.css
@@ -1,6 +1,6 @@
 /**
  * @file
- * TableSelect behavior.
+ * Table select behavior.
  *
  * @see tableselect.js
  */
diff --git a/core/modules/system/css/components/tablesort.theme.css b/core/modules/system/css/components/tablesort.theme.css
index edbf5ce..44e5349 100644
--- a/core/modules/system/css/components/tablesort.theme.css
+++ b/core/modules/system/css/components/tablesort.theme.css
@@ -1,11 +1,11 @@
 /**
  * @file
- * Markup generated by tablesort-indicator.html.twig.
+ * Table sort indicator.
  */
 
-th.active img {
+th.is-active img {
   display: inline;
 }
-td.active {
+td.is-active {
   background-color: #ddd;
 }
diff --git a/core/modules/system/css/components/tabs.theme.css b/core/modules/system/css/components/tabs.theme.css
index 23ebb76..d890864 100644
--- a/core/modules/system/css/components/tabs.theme.css
+++ b/core/modules/system/css/components/tabs.theme.css
@@ -24,7 +24,7 @@ ul.tabs {
   padding: 0.2em 1em;
   text-decoration: none;
 }
-.tabs a.active {
+.tabs a.is-active {
   background-color: #eee;
 }
 .tabs a:focus,
diff --git a/core/modules/system/css/components/textarea.theme.css b/core/modules/system/css/components/textarea.theme.css
index f52a9b7..1649ca7 100644
--- a/core/modules/system/css/components/textarea.theme.css
+++ b/core/modules/system/css/components/textarea.theme.css
@@ -1,6 +1,6 @@
 /**
  * @file
- * Visual styles for resizeable textarea.
+ * Visual styles for a resizeable textarea.
  */
 
 .form-textarea-wrapper textarea {
diff --git a/core/modules/system/css/components/tree-child.theme.css b/core/modules/system/css/components/tree-child.theme.css
index 4b37b6e..71bb8c8 100644
--- a/core/modules/system/css/components/tree-child.theme.css
+++ b/core/modules/system/css/components/tree-child.theme.css
@@ -1,6 +1,6 @@
 /**
  * @file
- * Visual styles for tree child.
+ * Visual styles for a nested tree child.
  */
 
 div.tree-child {
diff --git a/core/modules/system/system.libraries.yml b/core/modules/system/system.libraries.yml
index f8e74ef..e2c6f79 100644
--- a/core/modules/system/system.libraries.yml
+++ b/core/modules/system/system.libraries.yml
@@ -3,50 +3,49 @@ base:
   css:
     # Adjust the weights to load these early.
     component:
-      css/components/ajax-progress.module.css: { every_page: true, weight: -10, }
-      css/components/align.module.css: { every_page: true, weight: -10, }
-      css/components/animated-throbber.module.css: { every_page: true, weight: -10, }
-      css/components/fieldgroup.module.css: { every_page: true, weight: -10, }
-      css/components/container-inline.module.css: { every_page: true, weight: -10, }
-      css/components/clearfix.module.css: { every_page: true, weight: -10, }
-      css/components/details.module.css: { every_page: true, weight: -10, }
-      css/components/hidden.module.css: { every_page: true, weight: -10, }
-      css/components/js.module.css: { every_page: true, weight: -10, }
-      css/components/nowrap.module.css: { every_page: true, weight: -10, }
-      css/components/position-container.module.css: { every_page: true, weight: -10, }
-      css/components/progress.module.css: { every_page: true, weight: -10, }
-      css/components/reset-appearance.module.css: { every_page: true, weight: -10, }
-      css/components/resize.module.css: { every_page: true, weight: -10, }
-      css/components/sticky-header.css: { every_page: true, weight: -10, }
-      css/components/tabledrag.module.css: { every_page: true, weight: -10, }
+      css/components/ajax-progress.module.css: { every_page: true, weight: -10 }
+      css/components/align.module.css: { every_page: true, weight: -10 }
+      css/components/autocomplete-loading.module.css: { every_page: true, weight: -10 }
+      css/components/fieldgroup.module.css: { every_page: true, weight: -10 }
+      css/components/container-inline.module.css: { every_page: true, weight: -10 }
+      css/components/clearfix.module.css: { every_page: true, weight: -10 }
+      css/components/details.module.css: { every_page: true, weight: -10 }
+      css/components/hidden.module.css: { every_page: true, weight: -10 }
+      css/components/js.module.css: { every_page: true, weight: -10 }
+      css/components/nowrap.module.css: { every_page: true, weight: -10 }
+      css/components/position-container.module.css: { every_page: true, weight: -10 }
+      css/components/progress.module.css: { every_page: true, weight: -10 }
+      css/components/reset-appearance.module.css: { every_page: true, weight: -10 }
+      css/components/resize.module.css: { every_page: true, weight: -10 }
+      css/components/sticky-header.module.css: { every_page: true, weight: -10 }
+      css/components/tabledrag.module.css: { every_page: true, weight: -10 }
     theme:
-      css/components/action-links.theme.css: { every_page: true, weight: -10, }
-      css/components/breadcrumbs.theme.css: { every_page: true, weight: -10, }
-      css/components/button.theme.css: { every_page: true, weight: -10, }
-      css/components/collapse-processed.theme.css: { every_page: true, weight: -10, }
-      css/components/container-inline.theme.css: { every_page: true, weight: -10, }
-      css/components/details.theme.css: { every_page: true, weight: -10, }
-      css/components/exposed-filters.theme.css: { every_page: true, weight: -10, }
-      css/components/field.theme.css: { every_page: true, weight: -10, }
-      css/components/form.theme.css: { every_page: true, weight: -10, }
-      css/components/icons.theme.css: { every_page: true, weight: -10, }
-      css/components/inline-form.theme.css: { every_page: true, weight: -10, }
-      css/components/item-list.theme.css: { every_page: true, weight: -10, }
-      css/components/link.theme.css: { every_page: true, weight: -10, }
-      css/components/links.theme.css: { every_page: true, weight: -10, }
-      css/components/menu.theme.css: { every_page: true, weight: -10, }
-      css/components/messages.theme.css: { every_page: true, weight: -10, }
-      css/components/more-help.theme.css: { every_page: true, weight: -10, }
-      css/components/more-link.theme.css: { every_page: true, weight: -10, }
-      css/components/node.theme.css: { every_page: true, weight: -10, }
-      css/components/pager.theme.css: { every_page: true, weight: -10, }
-      css/components/progress.theme.css: { every_page: true, weight: -10, }
-      css/components/table-select.theme.css: { every_page: true, weight: -10, }
-      css/components/tabledrag.theme.css: { every_page: true, weight: -10, }
-      css/components/tablesort.theme.css: { every_page: true, weight: -10, }
-      css/components/tabs.theme.css: { every_page: true, weight: -10, }
-      css/components/textarea.theme.css: { every_page: true, weight: -10, }
-      css/components/tree-child.theme.css: { every_page: true, weight: -10, }
+      css/components/action-links.theme.css: { every_page: true, weight: -10 }
+      css/components/breadcrumb.theme.css: { every_page: true, weight: -10 }
+      css/components/button.theme.css: { every_page: true, weight: -10 }
+      css/components/collapse-processed.theme.css: { every_page: true, weight: -10 }
+      css/components/container-inline.theme.css: { every_page: true, weight: -10 }
+      css/components/details.theme.css: { every_page: true, weight: -10 }
+      css/components/exposed-filters.theme.css: { every_page: true, weight: -10 }
+      css/components/field.theme.css: { every_page: true, weight: -10 }
+      css/components/form.theme.css: { every_page: true, weight: -10 }
+      css/components/icons.theme.css: { every_page: true, weight: -10 }
+      css/components/inline-form.theme.css: { every_page: true, weight: -10 }
+      css/components/item-list.theme.css: { every_page: true, weight: -10 }
+      css/components/link.theme.css: { every_page: true, weight: -10 }
+      css/components/links.theme.css: { every_page: true, weight: -10 }
+      css/components/menu.theme.css: { every_page: true, weight: -10 }
+      css/components/messages.theme.css: { every_page: true, weight: -10 }
+      css/components/more-link.theme.css: { every_page: true, weight: -10 }
+      css/components/node.theme.css: { every_page: true, weight: -10 }
+      css/components/pager.theme.css: { every_page: true, weight: -10 }
+      css/components/progress.theme.css: { every_page: true, weight: -10 }
+      css/components/tableselect.theme.css: { every_page: true, weight: -10 }
+      css/components/tabledrag.theme.css: { every_page: true, weight: -10 }
+      css/components/tablesort.theme.css: { every_page: true, weight: -10 }
+      css/components/tabs.theme.css: { every_page: true, weight: -10 }
+      css/components/textarea.theme.css: { every_page: true, weight: -10 }
+      css/components/tree-child.theme.css: { every_page: true, weight: -10 }
 
 admin:
   version: VERSION