Stack's position to be relative by default so it's child can be anchored

dist/index.js

@@ -4023,7 +4023,9 @@ return __module.exports;
 
     class DoricStackNode extends DoricGroupViewNode {
         build() {
-            return document.createElement('div');
+            const ret = document.createElement('div');
+            ret.style.position = "relative";
+            return ret;
         }
         layout() {
             super.layout();

src/shader/DoricStackNode.ts

@@ -3,7 +3,9 @@ import { DoricGroupViewNode, LayoutSpec, FrameSize, LEFT, RIGHT, CENTER_X, CENTE
 export class DoricStackNode extends DoricGroupViewNode {
 
     build() {
-        return document.createElement('div')
+        const ret = document.createElement('div')
+        ret.style.position = "relative"
+        return ret
     }
 
     layout() {