Add theme assets;

public/assets/scss/theme-dark/components/plugin-overrides/_easymde.scss

@@ -0,0 +1,72 @@
+// npm package: easymde
+// github link: https://github.com/Ionaru/easy-markdown-editor
+
+.EasyMDEContainer .CodeMirror {
+  background: $input-bg;
+  border: 1px solid $input-border-color;
+  color: $body-color;
+  border-bottom-left-radius: 0;
+  border-bottom-right-radius: 0;
+}
+
+.editor-toolbar {
+  border: 1px solid $input-border-color;
+  border-bottom: 0;
+  border-radius: 4px 4px 0 0;
+  &, &:hover {
+    opacity: 1;
+  }
+  button {
+    color: rgba($body-color, .7) !important;
+    &:hover {
+      background: lighten($input-bg, 10%);
+      border-color: transparent;
+    }
+  }
+  i.separator {
+    border-left: 1px solid $input-border-color;
+    border-right: 1px solid $input-border-color;
+  }
+}
+
+.CodeMirror-fullscreen, 
+.editor-toolbar.fullscreen,
+.editor-preview-side {
+  z-index: 999;
+}
+
+.editor-toolbar.fullscreen,
+.editor-toolbar.fullscreen::before,
+.editor-toolbar.fullscreen::after {
+  background: $input-bg;
+}
+
+.CodeMirror-cursor {
+  border-color: $body-color;
+}
+
+.editor-toolbar.disabled-for-preview button:not(.no-disable) {
+  background: $input-bg;
+}
+.editor-toolbar button.active,
+.editor-toolbar button:hover {
+  background: lighten($input-bg, 10%);
+  border-color: transparent;
+}
+
+.editor-preview, 
+.editor-preview-side {
+  background: lighten($input-bg, 1%);
+}
+
+.editor-preview-side {
+  border-color: $input-border-color;
+}
+
+.editor-statusbar {
+  padding: 0 10px;
+  border: 1px solid $input-border-color;
+  border-top-color: transparent;
+  border-bottom-left-radius: $input-border-radius;
+  border-bottom-right-radius: $input-border-radius;
+}