diff --git a/theme/boost/scss/editor.scss b/theme/boost/scss/editor.scss
index b5a870aeb93..2ffd9074192 100644
--- a/theme/boost/scss/editor.scss
+++ b/theme/boost/scss/editor.scss
@@ -17,3 +17,10 @@ table:not(.table) {
         border-width: $table-border-width;
     }
 }
+
+code[data-mce-selected="inline-boundary"]:not(pre code) {
+    background-color: $gray-100 !important; /* stylelint-disable-line declaration-no-important */
+    border: thin solid $gray-500;
+    border-radius: 0.25rem;
+    padding: 0.125rem;
+}