diff --git a/src/sandbox/scoped_css.ts b/src/sandbox/scoped_css.ts
index 7e9bdeb1..c9c61e0f 100644
--- a/src/sandbox/scoped_css.ts
+++ b/src/sandbox/scoped_css.ts
@@ -524,7 +524,7 @@ export default function scopedCSS (
           scopedCSS(styleElement, app, linkPath)
         }
       })
-      observer.observe(styleElement, { childList: true, characterData: true })
+      observer.observe(styleElement, { childList: true, characterData: true, subtree: true })
     } else {
       const observer = new MutationObserver(function () {
         observer.disconnect()