diff --git a/demo/visualizing-set-relations.html b/demo/visualizing-set-relations.html
index 61984af..7447e85 100644
--- a/demo/visualizing-set-relations.html
+++ b/demo/visualizing-set-relations.html
@@ -44,11 +44,11 @@
     <folk-shape x="100" y="300" width="50" height="50"></folk-shape>
     <folk-hull sources="h1, body > folk-shape"></folk-hull>
 
-    <!-- <folk-hull sources="h1">
+    <folk-hull sources="h1">
       <folk-shape x="350" y="100" width="50" height="50"></folk-shape>
       <folk-shape x="500" y="200" width="50" height="50"></folk-shape>
       <folk-shape x="400" y="300" width="50" height="50"></folk-shape>
-    </folk-hull> -->
+    </folk-hull>
 
     <script type="module">
       import '../src/standalone/folk-shape.ts';
diff --git a/src/folk-base-set.ts b/src/folk-base-set.ts
index afc5ab2..9f6e094 100644
--- a/src/folk-base-set.ts
+++ b/src/folk-base-set.ts
@@ -1,28 +1,13 @@
+import { property, state } from '@lit/reactive-element/decorators.js';
 import { ClientRectObserverEntry } from './common/client-rect-observer.ts';
+import { FolkElement } from './common/folk-element.ts';
 import { FolkObserver } from './common/folk-observer.ts';
+import { PropertyValues } from '@lit/reactive-element';
 
 const folkObserver = new FolkObserver();
 
-const defaultRect = DOMRectReadOnly.fromRect();
-
-export class FolkBaseSet extends HTMLElement {
-  static tagName = '';
-
-  static define() {
-    if (customElements.get(this.tagName)) return;
-    customElements.define(this.tagName, this);
-  }
-
-  #sources = this.getAttribute('sources') || '';
-  /** A CSS selector for the sources of the arrow. */
-  get sources() {
-    return this.#sources;
-  }
-
-  set sources(sources) {
-    this.#sources = sources;
-    this.observeSources();
-  }
+export class FolkBaseSet extends FolkElement {
+  @property({ type: String, reflect: true }) sources = '';
 
   #sourcesMap = new Map<Element, DOMRectReadOnly>();
   get sourcesMap(): ReadonlyMap<Element, DOMRectReadOnly> {
@@ -33,34 +18,32 @@ export class FolkBaseSet extends HTMLElement {
     return Array.from(this.#sourcesMap.values());
   }
 
-  #sourceElements = new Set<Element>();
-  get sourceElements(): ReadonlySet<Element> {
-    return this.#sourceElements;
-  }
+  @state() sourceElements = new Set<Element>();
 
   #sourcesCallback = (entry: ClientRectObserverEntry) => {
     this.#sourcesMap.set(entry.target, entry.contentRect);
-    if (this.#sourceElements.size === this.#sourcesMap.size) {
-      this.update();
-    }
+    this.requestUpdate();
   };
 
-  connectedCallback() {
-    this.observeSources();
-  }
-
   disconnectedCallback() {
+    super.disconnectedCallback();
     this.unobserveSources();
   }
 
+  override update(changedProperties: PropertyValues<this>) {
+    super.update(changedProperties);
+
+    if (changedProperties.has('sources')) {
+      this.observeSources();
+    }
+  }
+
   observeSources() {
-    const elements = this.sources ? document.querySelectorAll(this.sources) : [];
     const childElements = new Set(this.children);
+    const elements = this.sources ? document.querySelectorAll(this.sources) : [];
     const sourceElements = new Set(elements).union(childElements);
-
-    const elementsToObserve = sourceElements.difference(this.#sourceElements);
-
-    const elementsToUnobserve = this.#sourceElements.difference(sourceElements);
+    const elementsToObserve = sourceElements.difference(this.sourceElements);
+    const elementsToUnobserve = this.sourceElements.difference(sourceElements);
 
     this.unobserveSources(elementsToUnobserve);
 
@@ -68,16 +51,14 @@ export class FolkBaseSet extends HTMLElement {
       folkObserver.observe(el, this.#sourcesCallback);
     }
 
-    this.#sourceElements = sourceElements;
+    this.sourceElements = sourceElements;
   }
 
-  unobserveSources(elements: Set<Element> = this.#sourceElements) {
+  unobserveSources(elements: Set<Element> = this.sourceElements) {
     for (const el of elements) {
       folkObserver.unobserve(el, this.#sourcesCallback);
       this.#sourcesMap.delete(el);
-      this.#sourceElements.delete(el);
+      this.sourceElements.delete(el);
     }
   }
-
-  update() {}
 }
diff --git a/src/folk-distance-field.ts b/src/folk-distance-field.ts
index 822b31e..dfd6ae4 100644
--- a/src/folk-distance-field.ts
+++ b/src/folk-distance-field.ts
@@ -4,6 +4,7 @@ import { glsl } from './common/tags.ts';
 import { WebGLUtils } from './common/webgl.ts';
 import { FolkBaseSet } from './folk-base-set.ts';
 import { FolkShape } from './folk-shape.ts';
+import { PropertyValues } from '@lit/reactive-element';
 
 /**
  * The DistanceField class calculates a distance field using the Jump Flooding Algorithm (JFA) in WebGL.
@@ -76,7 +77,11 @@ export class FolkDistanceField extends FolkBaseSet {
   /**
    * Handles updates to geometry elements by re-initializing seed points and rerunning the JFA.
    */
-  override update() {
+  override update(changedProperties: PropertyValues<this>) {
+    super.update(changedProperties);
+
+    if (this.sourcesMap.size !== this.sourceElements.size) return;
+
     this.populateSeedPoints();
     this.runJumpFloodingAlgorithm();
   }
diff --git a/src/folk-hull.ts b/src/folk-hull.ts
index b193105..ea26c25 100644
--- a/src/folk-hull.ts
+++ b/src/folk-hull.ts
@@ -1,7 +1,7 @@
 import { FolkBaseSet } from './folk-base-set';
 import { verticesToPolygon } from './common/utils';
 import type { Point } from './common/types';
-import { css, html } from './common/tags';
+import { PropertyValues, css } from '@lit/reactive-element';
 
 declare global {
   interface HTMLElementTagNameMap {
@@ -9,44 +9,40 @@ declare global {
   }
 }
 
-const styles = css`
-  :host {
-    pointer-events: none;
-  }
-
-  #hull {
-    background-color: var(--folk-hull-bg, #b4d8f644);
-    height: 100%;
-    width: 100%;
-  }
-
-  ::slotted(*) {
-    pointer-events: auto;
-  }
-`;
-
 export class FolkHull extends FolkBaseSet {
   static tagName = 'folk-hull';
 
+  static styles = css`
+    :host {
+      pointer-events: none;
+    }
+
+    #hull {
+      background-color: var(--folk-hull-bg, #b4d8f644);
+      height: 100%;
+      width: 100%;
+    }
+
+    ::slotted(*) {
+      pointer-events: auto;
+    }
+  `;
+
   #hull: Point[] = [];
 
   get hull(): ReadonlyArray<Point> {
     return this.#hull;
   }
 
-  #shadow = this.attachShadow({ mode: 'open' });
-
   #slot = document.createElement('slot');
   #hullEl = document.createElement('div');
 
-  constructor() {
-    super();
+  override firstUpdated(changedProperties: PropertyValues<this>): void {
+    super.firstUpdated(changedProperties);
 
     this.#hullEl.id = 'hull';
 
-    this.#shadow.adoptedStyleSheets.push(styles);
-
-    this.#shadow.append(this.#hullEl, this.#slot);
+    this.renderRoot.append(this.#hullEl, this.#slot);
 
     this.#slot.addEventListener('slotchange', this.#onSlotchange);
   }
@@ -54,14 +50,15 @@ export class FolkHull extends FolkBaseSet {
   // we might not need to react to the first slot change
   #onSlotchange = () => this.observeSources();
 
-  update() {
-    if (this.sourcesMap.size === 0) {
+  override update(changedProperties: PropertyValues<this>) {
+    super.update(changedProperties);
+
+    if (this.sourcesMap.size !== this.sourceElements.size) {
       this.style.clipPath = '';
       return;
     }
 
-    const rects = Array.from(this.sourcesMap.values());
-    this.#hull = makeHull(rects);
+    this.#hull = makeHull(this.sourceRects);
     this.#hullEl.style.clipPath = verticesToPolygon(this.#hull);
   }
 }