first commit

web/core/modules/media/css/filter.caption.css

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+/**
+ * @file
+ * Caption filter: default styling for displaying Media Embed captions.
+ */
+
+.caption .media .field,
+.caption .media .field * {
+  float: none;
+  margin: unset;
+}

web/core/modules/media/css/oembed.formatter.css

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+.media-oembed-content {
+  max-width: 100%;
+}

web/core/modules/media/css/oembed.frame.css

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+iframe {
+  position: absolute;
+  top: 0;
+  left: 0;
+  width: 100%;
+  height: 100%;
+  margin: 0;
+}

web/core/modules/media/css/plugins/drupalmedia/ckeditor.drupalmedia.css

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+/**
+ * @file
+ * Media embed: overrides to make focus styles and alignment work in CKEditor.
+ */
+
+/**
+ * Allow the drupal-media element's width to collapse to the size of its
+ * contents so that the outline has no extra white space (margin). This
+ * emulates the image2 plugin's styles inherited by the drupallink CKEditor
+ * plugin.
+ */
+drupal-media {
+  display: inline-block;
+}
+
+/**
+ * For center alignment, take advantage of drupal-media's inline-block
+ * display and center it as if it were text.
+ */
+.cke_widget_drupalmedia.align-center {
+  text-align: center;
+}
+
+/**
+ * Fix positioning without delete button. Can be removed with this issue:
+ * @see https://www.drupal.org/project/drupal/issues/3074859
+ */
+drupal-media .media-library-item__edit {
+  right: 10px;
+}
+
+/**
+ * Allow alignment to display in CKEditor.
+ */
+drupal-media[data-align=left],
+drupal-media[data-align=right] {
+  display: inline;
+}
+drupal-media[data-align=center] {
+  display: flex;
+}