diff --git a/core/themes/classy/templates/checkboxes.html.twig b/core/themes/classy/templates/checkboxes.html.twig
new file mode 100644
index 0000000..7c56355
--- /dev/null
+++ b/core/themes/classy/templates/checkboxes.html.twig
@@ -0,0 +1,17 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a 'checkboxes' #type form element.
+ *
+ * Available variables
+ * - attributes: A list of HTML attributes for the wrapper element.
+ * - children: The rendered checkboxes.
+ *
+ * @see template_preprocess_checkboxes()
+ *
+ * @ingroup themeable
+ */
+ @todo: remove this file once http://drupal.org/node/1819284 is resolved.
+ This is identical to core/modules/system/templates/container.html.twig
+#}
+<div{{ attributes.addClass('form-checkboxes') }}>{{ children }}</div>
diff --git a/core/themes/classy/templates/confirm-form.html.twig b/core/themes/classy/templates/confirm-form.html.twig
new file mode 100644
index 0000000..d714917
--- /dev/null
+++ b/core/themes/classy/templates/confirm-form.html.twig
@@ -0,0 +1,15 @@
+{#
+/**
+ * @file
+ * Default theme implementation for confirm form.
+ *
+ * By default this does not alter the appearance of a form at all,
+ * but is provided as a convenience for themers.
+ *
+ * Available variables:
+ * - form: The confirm form.
+ *
+ * @ingroup themeable
+ */
+#}
+{{ form }}
diff --git a/core/themes/classy/templates/container.html.twig b/core/themes/classy/templates/container.html.twig
new file mode 100644
index 0000000..6fb8159
--- /dev/null
+++ b/core/themes/classy/templates/container.html.twig
@@ -0,0 +1,20 @@
+{#
+/**
+ * @file
+ * Default theme implementation of a container used to wrap child elements.
+ *
+ * Used for grouped form items. Can also be used as a #theme_wrapper for any
+ * renderable element, to surround it with a <div> and HTML attributes.
+ *
+ * Available variables:
+ * - attributes: HTML attributes for the containing element.
+ * - children: The rendered child elements of the container.
+ * - has_parent: A flag to indicate that the container has one or more parent
+     containers.
+ *
+ * @see template_preprocess_container()
+ *
+ * @ingroup themeable
+ */
+#}
+<div{{ attributes.addClass(has_parent ? 'form-wrapper') }}>{{ children }}</div>