diff --git a/demo/index.html b/demo/index.html
index 78a506d..8357298 100644
--- a/demo/index.html
+++ b/demo/index.html
@@ -32,6 +32,7 @@
       <li><a href="spreadsheet.html">Spreadsheet</a></li>
       <li><a href="spreadsheet-graph.html">Spreadsheet Graph</a></li>
       <li><a href="spreadsheet-propagator.html">Spreadsheet Propagator</a></li>
+      <li><a href="wiggly.html">Wiggly</a></li>
       <!-- <li><a href="chains-of-thought/index.html">Chains of thought</a></li> -->
     </ul>
   </body>
diff --git a/src/canvas/fc-geometry.ts b/src/canvas/fc-geometry.ts
index ce34bb8..faaece3 100644
--- a/src/canvas/fc-geometry.ts
+++ b/src/canvas/fc-geometry.ts
@@ -1,45 +1,4 @@
-export type ResizeObserverEntryCallback = (entry: ResizeObserverEntry) => void;
-
-class ResizeObserverManager {
-  #elementMap = new WeakMap<Element, Set<ResizeObserverEntryCallback>>();
-  #elementEntry = new WeakMap<Element, ResizeObserverEntry>();
-
-  #vo = new ResizeObserver((entries) => {
-    for (const entry of entries) {
-      this.#elementEntry.set(entry.target, entry);
-      this.#elementMap.get(entry.target)?.forEach((callback) => callback(entry));
-    }
-  });
-
-  observe(target: Element, callback: ResizeObserverEntryCallback): void {
-    let callbacks = this.#elementMap.get(target);
-
-    if (callbacks === undefined) {
-      this.#vo.observe(target);
-      this.#elementMap.set(target, (callbacks = new Set()));
-    } else {
-      const entry = this.#elementEntry.get(target);
-      if (entry) {
-        callback(entry);
-      }
-    }
-
-    callbacks.add(callback);
-  }
-
-  unobserve(target: Element, callback: ResizeObserverEntryCallback): void {
-    const callbacks = this.#elementMap.get(target);
-
-    if (callbacks === undefined) return;
-
-    callbacks.delete(callback);
-
-    if (callbacks.size === 0) {
-      this.#vo.unobserve(target);
-      this.#elementMap.delete(target);
-    }
-  }
-}
+import { ResizeObserverManager } from '../resize-observer';
 
 const resizeObserver = new ResizeObserverManager();
 
diff --git a/src/resize-observer.ts b/src/resize-observer.ts
new file mode 100644
index 0000000..a721505
--- /dev/null
+++ b/src/resize-observer.ts
@@ -0,0 +1,42 @@
+export type ResizeObserverEntryCallback = (entry: ResizeObserverEntry) => void;
+
+export class ResizeObserverManager {
+  #elementMap = new WeakMap<Element, Set<ResizeObserverEntryCallback>>();
+  #elementEntry = new WeakMap<Element, ResizeObserverEntry>();
+
+  #vo = new ResizeObserver((entries) => {
+    for (const entry of entries) {
+      this.#elementEntry.set(entry.target, entry);
+      this.#elementMap.get(entry.target)?.forEach((callback) => callback(entry));
+    }
+  });
+
+  observe(target: Element, callback: ResizeObserverEntryCallback): void {
+    let callbacks = this.#elementMap.get(target);
+
+    if (callbacks === undefined) {
+      this.#vo.observe(target);
+      this.#elementMap.set(target, (callbacks = new Set()));
+    } else {
+      const entry = this.#elementEntry.get(target);
+      if (entry) {
+        callback(entry);
+      }
+    }
+
+    callbacks.add(callback);
+  }
+
+  unobserve(target: Element, callback: ResizeObserverEntryCallback): void {
+    const callbacks = this.#elementMap.get(target);
+
+    if (callbacks === undefined) return;
+
+    callbacks.delete(callback);
+
+    if (callbacks.size === 0) {
+      this.#vo.unobserve(target);
+      this.#elementMap.delete(target);
+    }
+  }
+}