diff --git a/src/sandbox/index.js b/src/sandbox/index.js
index a3d63d9..8cf8248 100644
--- a/src/sandbox/index.js
+++ b/src/sandbox/index.js
@@ -192,7 +192,7 @@ class Sandbox extends Component {
   contentLoaded(ev) {
     let elem = ev.target
     let body = elem.contentDocument.body
-    elem.style.height = body.clientHeight + 'px'
+    elem.style.height = body.scrollHeight + 10 + 'px'
   }
 
   renderTemplate() {
@@ -207,9 +207,17 @@ class Sandbox extends Component {
 
   mounted() {
     //
-    this.#cache.preview.panel = this.$refs.preview
+    let target = this.$refs.preview
+    this.#cache.preview.panel = target
     this.renderTemplate()
-    this.$refs.preview.style.display = 'block'
+    target.style.display = 'block'
+
+    this.__observer = new ResizeObserver(_ => this.contentLoaded({ target }))
+    this.__observer.observe(target.contentDocument.body)
+  }
+
+  unmounted() {
+    this.__observer?.disconnect()
   }
 
   render() {