diff -u b/core/modules/filter/templates/filter-caption.html.twig b/core/modules/filter/templates/filter-caption.html.twig
--- b/core/modules/filter/templates/filter-caption.html.twig
+++ b/core/modules/filter/templates/filter-caption.html.twig
@@ -12,7 +12,7 @@
  * - string classes: The classes of the captioned HTML tag.
  */
 #}
-<figure>
+<figure{%- if classes %} class="{{ classes }}"{%- endif %}>
 {{ node }}
 <figcaption>{{ caption }}</figcaption>
 </figure>
reverted:
--- b/core/themes/classy/templates/filter-caption.html.twig
+++ /dev/null
@@ -1,18 +0,0 @@
-{#
-/**
- * @file
- * Default theme implementation for a filter caption.
- *
- * Returns HTML for a captioned image, audio, video or other tag.
- *
- * Available variables
- * - string node: The complete HTML tag whose contents are being captioned.
- * - string tag: The name of the HTML tag whose contents are being captioned.
- * - string caption: The caption text.
- * - string classes: The classes of the captioned HTML tag.
- */
-#}
-<figure class="caption caption-{{ tag }}{%- if classes %} {{ classes }}{%- endif %}">
-{{ node }}
-<figcaption>{{ caption }}</figcaption>
-</figure>
reverted:
--- b/core/themes/classy/templates/filter-guidelines.html.twig
+++ /dev/null
@@ -1,31 +0,0 @@
-{#
-/**
- * @file
- * Default theme implementation for guidelines for a text format.
- *
- * Available variables:
- * - format: Contains information about the current text format, including the
- *   following:
- *   - name: The name of the text format, potentially unsafe and needs to be
- *     escaped.
- *   - format: The machine name of the text format, e.g. 'basic_html'.
- * - attributes: HTML attributes for the containing element.
- * - tips: Descriptions and a CSS ID in the form of 'module-name/filter-id'
- *   (only used when 'long' is TRUE) for each filter in one or more text
- *   formats.
- *
- * @see template_preprocess_filter_tips()
- *
- * @ingroup themeable
- */
-#}
-{%
-  set classes = [
-    'filter-guidelines-item',
-    'filter-guidelines-' ~ format.format,
-  ]
-%}
-<div{{ attributes.addClass(classes) }}>
-  <h4 class="label">{{ format.name }}</h4>
-  {{ tips }}
-</div>
reverted:
--- b/core/themes/classy/templates/filter-tips.html.twig
+++ /dev/null
@@ -1,63 +0,0 @@
-{#
-/**
- * @file
- * Default theme implementation for a set of filter tips.
- *
- * Available variables:
- * - tips: Descriptions and a CSS ID in the form of 'module-name/filter-id'
- *   (only used when 'long' is TRUE) for each filter in one or more text
- *   formats.
- * - long: A flag indicating whether the passed-in filter tips contain extended
- *   explanations, i.e. intended to be output on the path 'filter/tips'
- *   (TRUE), or are in a short format, i.e. suitable to be displayed below a
- *   form element. Defaults to FALSE.
- * - multiple: A flag indicating there is more than one filter tip.
- *
- * @see template_preprocess_filter_tips()
- *
- * @ingroup themeable
- */
-#}
-{% if multiple %}
-  <h2>{{ 'Text Formats'|t }}</h2>
-{% endif %}
-
-{% if tips|length %}
-  {% if multiple %}
-    <div class="compose-tips">
-  {% endif %}
-
-  {% for name, tip in tips %}
-    {% if multiple %}
-      {%
-        set tip_classes = [
-          'filter-type',
-          'filter-' ~ name|clean_class,
-        ]
-      %}
-      <div{{ tip.attributes.addClass(tip_classes) }}>
-      <h3>{{ tip.name }}</h3>
-    {% endif %}
-
-    {% if tip.list|length %}
-      <ul class="tips">
-      {% for item in tip.list %}
-        {%
-          set item_classes = [
-            long ? 'filter-' ~ item.id|replace({'/': '-'}),
-          ]
-        %}
-        <li{{ item.attributes.addClass(item_classes) }}>{{ item.tip }}</li>
-      {% endfor %}
-      </ul>
-    {% endif %}
-
-    {% if multiple %}
-      </div>
-    {% endif %}
-  {% endfor %}
-
-  {% if multiple %}
-    </div>
-  {% endif %}
-{% endif %}
reverted:
--- b/core/themes/classy/templates/text-format-wrapper.html.twig
+++ /dev/null
@@ -1,28 +0,0 @@
-{#
-/**
- * @file
- * Default theme implementation for a text format-enabled form element.
- *
- * Available variables:
- * - children: Text format element children.
- * - description: Text format element description.
- * - attributes: HTML attributes for the containing element.
- * - aria_description: Flag for whether or not an ARIA description has been
- *   added to the description container.
- *
- * @see template_preprocess_text_format_wrapper()
- *
- * @ingroup themeable
- */
-#}
-<div class="text-format-wrapper form-item">
-  {{ children }}
-  {% if description %}
-    {%
-      set classes = [
-        aria_description ? 'description',
-      ]
-    %}
-    <div{{ attributes.addClass(classes) }}>{{ description }}</div>
-  {% endif %}
-</div>
only in patch2:
unchanged:
--- a/core/modules/filter/src/Tests/FilterUnitTest.php
+++ b/core/modules/filter/src/Tests/FilterUnitTest.php
@@ -118,7 +118,7 @@ function testCaptionFilter() {
 
     // Data-caption attribute.
     $input = '<img src="llama.jpg" data-caption="Loquacious llama!" />';
-    $expected = '<figure class="caption caption-img"><img src="llama.jpg" /><figcaption>Loquacious llama!</figcaption></figure>';
+    $expected = '<figure><img src="llama.jpg" /><figcaption>Loquacious llama!</figcaption></figure>';
     $output = $test($input);
     $this->assertIdentical($expected, $output->getProcessedText());
     $this->assertIdentical($attached_library, $output->getAssets());
@@ -130,14 +130,14 @@ function testCaptionFilter() {
 
     // HTML entities in the caption.
     $input = '<img src="llama.jpg" data-caption="&ldquo;Loquacious llama!&rdquo;" />';
-    $expected = '<figure class="caption caption-img"><img src="llama.jpg" /><figcaption>“Loquacious llama!”</figcaption></figure>';
+    $expected = '<figure><img src="llama.jpg" /><figcaption>“Loquacious llama!”</figcaption></figure>';
     $output = $test($input);
     $this->assertIdentical($expected, $output->getProcessedText());
     $this->assertIdentical($attached_library, $output->getAssets());
 
     // HTML encoded as HTML entities in data-caption attribute.
     $input = '<img src="llama.jpg" data-caption="&lt;em&gt;Loquacious llama!&lt;/em&gt;" />';
-    $expected = '<figure class="caption caption-img"><img src="llama.jpg" /><figcaption><em>Loquacious llama!</em></figcaption></figure>';
+    $expected = '<figure><img src="llama.jpg" /><figcaption><em>Loquacious llama!</em></figcaption></figure>';
     $output = $test($input);
     $this->assertIdentical($expected, $output->getProcessedText());
     $this->assertIdentical($attached_library, $output->getAssets());
@@ -146,33 +146,33 @@ function testCaptionFilter() {
     // not allowed by the HTML spec, but may happen when people manually write
     // HTML, so we explicitly support it.
     $input = '<img src="llama.jpg" data-caption="<em>Loquacious llama!</em>" />';
-    $expected = '<figure class="caption caption-img"><img src="llama.jpg" /><figcaption><em>Loquacious llama!</em></figcaption></figure>';
+    $expected = '<figure><img src="llama.jpg" /><figcaption><em>Loquacious llama!</em></figcaption></figure>';
     $output = $test($input);
     $this->assertIdentical($expected, $output->getProcessedText());
     $this->assertIdentical($attached_library, $output->getAssets());
 
     // Security test: attempt an XSS.
     $input = '<img src="llama.jpg" data-caption="<script>alert(\'Loquacious llama!\')</script>" />';
-    $expected = '<figure class="caption caption-img"><img src="llama.jpg" /><figcaption>alert(\'Loquacious llama!\')</figcaption></figure>';
+    $expected = '<figure><img src="llama.jpg" /><figcaption>alert(\'Loquacious llama!\')</figcaption></figure>';
     $output = $test($input);
     $this->assertIdentical($expected, $output->getProcessedText());
     $this->assertIdentical($attached_library, $output->getAssets());
 
     // Ensure the filter also works with uncommon yet valid attribute quoting.
     $input = '<img src=llama.jpg data-caption=\'Loquacious llama!\' />';
-    $expected = '<figure class="caption caption-img"><img src="llama.jpg" /><figcaption>Loquacious llama!</figcaption></figure>';
+    $expected = '<figure><img src="llama.jpg" /><figcaption>Loquacious llama!</figcaption></figure>';
     $output = $test($input);
     $this->assertIdentical($expected, $output->getProcessedText());
     $this->assertIdentical($attached_library, $output->getAssets());
 
     // Finally, ensure that this also works on any other tag.
     $input = '<video src="llama.jpg" data-caption="Loquacious llama!" />';
-    $expected = '<figure class="caption caption-video"><video src="llama.jpg"></video><figcaption>Loquacious llama!</figcaption></figure>';
+    $expected = '<figure><video src="llama.jpg"></video><figcaption>Loquacious llama!</figcaption></figure>';
     $output = $test($input);
     $this->assertIdentical($expected, $output->getProcessedText());
     $this->assertIdentical($attached_library, $output->getAssets());
     $input = '<foobar data-caption="Loquacious llama!">baz</foobar>';
-    $expected = '<figure class="caption caption-foobar"><foobar>baz</foobar><figcaption>Loquacious llama!</figcaption></figure>';
+    $expected = '<figure><foobar>baz</foobar><figcaption>Loquacious llama!</figcaption></figure>';
     $output = $test($input);
     $this->assertIdentical($expected, $output->getProcessedText());
     $this->assertIdentical($attached_library, $output->getAssets());
@@ -198,17 +198,17 @@ function testAlignAndCaptionFilters() {
     // Both data-caption and data-align attributes: all 3 allowed values for the
     // data-align attribute.
     $input = '<img src="llama.jpg" data-caption="Loquacious llama!" data-align="left" />';
-    $expected = '<figure class="caption caption-img align-left"><img src="llama.jpg" /><figcaption>Loquacious llama!</figcaption></figure>';
+    $expected = '<figure class="align-left"><img src="llama.jpg" /><figcaption>Loquacious llama!</figcaption></figure>';
     $output = $test($input);
     $this->assertIdentical($expected, $output->getProcessedText());
     $this->assertIdentical($attached_library, $output->getAssets());
     $input = '<img src="llama.jpg" data-caption="Loquacious llama!" data-align="center" />';
-    $expected = '<figure class="caption caption-img align-center"><img src="llama.jpg" /><figcaption>Loquacious llama!</figcaption></figure>';
+    $expected = '<figure class="align-center"><img src="llama.jpg" /><figcaption>Loquacious llama!</figcaption></figure>';
     $output = $test($input);
     $this->assertIdentical($expected, $output->getProcessedText());
     $this->assertIdentical($attached_library, $output->getAssets());
     $input = '<img src="llama.jpg" data-caption="Loquacious llama!" data-align="right" />';
-    $expected = '<figure class="caption caption-img align-right"><img src="llama.jpg" /><figcaption>Loquacious llama!</figcaption></figure>';
+    $expected = '<figure class="align-right"><img src="llama.jpg" /><figcaption>Loquacious llama!</figcaption></figure>';
     $output = $test($input);
     $this->assertIdentical($expected, $output->getProcessedText());
     $this->assertIdentical($attached_library, $output->getAssets());
@@ -216,7 +216,7 @@ function testAlignAndCaptionFilters() {
     // Both data-caption and data-align attributes, but a disallowed data-align
     // attribute value.
     $input = '<img src="llama.jpg" data-caption="Loquacious llama!" data-align="left foobar" />';
-    $expected = '<figure class="caption caption-img"><img src="llama.jpg" /><figcaption>Loquacious llama!</figcaption></figure>';
+    $expected = '<figure><img src="llama.jpg" /><figcaption>Loquacious llama!</figcaption></figure>';
     $output = $test($input);
     $this->assertIdentical($expected, $output->getProcessedText());
     $this->assertIdentical($attached_library, $output->getAssets());