fix: fixed-size canvas + reliable init

index.html

@@ -270,6 +270,7 @@ button { font-family: inherit; cursor: pointer; border: none; background: none;
 #drakon-canvas {
   width: 100%;
   height: 420px;
+  position: relative;
 }
 
 @media (max-width: 768px) {
@@ -1415,7 +1416,7 @@ function initDrakonDiagram() {
 
   // Minimal view-only configuration
   var config = {
-    startEditContent: function () { /* read-only — no edit */ },
+    startEditContent: function () { /* read-only */ },
     showContextMenu: function () { /* read-only */ },
     canSelect: false,
     maxWidth: 320,
@@ -1447,15 +1448,12 @@ function initDrakonDiagram() {
   // Build widget
   var drakonCanvas = document.getElementById('drakon-canvas');
   var drakon = createDrakonWidget();
+  var WIDGET_W = 560;
+  var WIDGET_H = 420;
 
   function rebuildWidget() {
-    var rect = drakonCanvas.getBoundingClientRect();
     drakonCanvas.innerHTML = '';
-    var widgetEl = drakon.render(
+    var widgetEl = drakon.render(WIDGET_W, WIDGET_H, config);
-      rect.width || 600,
-      rect.height || 420,
-      config
-    );
     drakonCanvas.appendChild(widgetEl);
   }
 
@@ -1479,7 +1477,7 @@ function initDrakonDiagram() {
       sender,
       false
     );
-  }, 100);
+  }, 200);
 
   // Handle resize
   var resizeObserver = new ResizeObserver(function () {