Fix heading display

packages/docs/lib/main.scss

@@ -22,6 +22,7 @@ html {
   --fg: var(--black);
 
   --interact: #3f9cff;
+  --interact-lite: #3f9cff;
 
   --z-context-menu: 3000;
 }

packages/heading/lib/display.ts

@@ -36,7 +36,7 @@ export default defineComponent({
     return () => h(
       `h${props.data.level}`,
       {
-        class: classes,
+        class: classes.value,
         innerHTML: props.data.value,
       },
     );