diff --git a/src/modules/esl-popup/core/esl-popup.ts b/src/modules/esl-popup/core/esl-popup.ts
index 397c9d210..e40801f03 100644
--- a/src/modules/esl-popup/core/esl-popup.ts
+++ b/src/modules/esl-popup/core/esl-popup.ts
@@ -1,9 +1,12 @@
 import {ExportNs} from '../../esl-utils/environment/export-ns';
 import {attr, jsonAttr} from '../../esl-base-element/core';
+import {bind} from '../../esl-utils/decorators/bind';
 import {prop} from '../../esl-utils/decorators/prop';
 import {rafDecorator} from '../../esl-utils/async/raf';
 import {ESLToggleable} from '../../esl-toggleable/core';
 
+import {listScrollParents} from './listScrollParents';
+
 import type {ToggleableActionParams} from '../../esl-toggleable/core';
 
 export interface PopupActionParams extends ToggleableActionParams {
@@ -17,6 +20,11 @@ export interface PopupActionParams extends ToggleableActionParams {
   offsetWindow?: number;
 }
 
+export interface ActivatorObserver {
+  unsubscribers?: (() => void)[];
+  observer?: IntersectionObserver;
+}
+
 @ExportNs('Popup')
 export class ESLPopup extends ESLToggleable {
   public static is = 'esl-popup';
@@ -27,6 +35,12 @@ export class ESLPopup extends ESLToggleable {
   protected _offsetWindow: number;
   protected _deferredUpdatePosition = rafDecorator(() => this._updatePosition());
 
+  protected _left: number;
+  protected _top: number;
+  protected _leftT: number;
+  protected _topT: number;
+  protected _activatorObserver: ActivatorObserver;
+
   @attr({defaultValue: 'top'}) public position: string;
   @attr({defaultValue: 'fit'}) public behavior: string;
 
@@ -41,19 +55,23 @@ export class ESLPopup extends ESLToggleable {
   @prop() public closeOnOutsideAction = true;
 
   public connectedCallback() {
-    this.$arrow = this.querySelector('.esl-popup-arrow');
-
     super.connectedCallback();
+
+    setTimeout(() => {
+      this.$arrow = this.querySelector('span.esl-popup-arrow');
+    });
   }
 
   protected bindEvents() {
     super.bindEvents();
     window.addEventListener('resize', this._deferredUpdatePosition);
+    window.addEventListener('scroll', this._deferredUpdatePosition);
   }
 
   protected unbindEvents() {
     super.unbindEvents();
     window.removeEventListener('resize', this._deferredUpdatePosition);
+    window.removeEventListener('scroll', this._deferredUpdatePosition);
   }
 
   // TODO: move to utilities
@@ -61,6 +79,10 @@ export class ESLPopup extends ESLToggleable {
     return document.documentElement.clientWidth || document.body.clientWidth;
   }
 
+  protected get _windowBottom() {
+    return window.pageYOffset + window.innerHeight;
+  }
+
   public onShow(params: PopupActionParams) {
     super.onShow(params);
 
@@ -74,6 +96,57 @@ export class ESLPopup extends ESLToggleable {
     this._offsetWindow = params.offsetWindow || 0;
 
     this._updatePosition();
+    this.activator && this._addActivatorObserver(this.activator);
+  }
+
+  public onHide(params: PopupActionParams) {
+    super.onHide(params);
+
+    this.activator && this._removeActivatorObserver(this.activator);
+  }
+
+  @bind
+  protected onActivatorIntersection(entries: IntersectionObserverEntry[], observer: IntersectionObserver) {
+    if (!entries[0].isIntersecting) {
+      this.hide();
+    }
+  }
+
+  @bind
+  protected onActivatorScroll(e: Event) {
+    this._updatePosition();
+  }
+
+  protected _addActivatorObserver(target: HTMLElement) {
+    const scrollParents = listScrollParents(target);
+
+    const unsubscribers = scrollParents.map(($root) => {
+      const options = {passive: true} as EventListenerOptions;
+      $root.addEventListener('scroll', this.onActivatorScroll, options);
+      return () => {
+        $root && $root.removeEventListener('scroll', this.onActivatorScroll, options);
+      };
+    });
+
+    const options = {
+      rootMargin: `-${this._offsetWindow}px`,
+      threshold: 1.0
+    } as IntersectionObserverInit;
+
+    const observer = new IntersectionObserver(this.onActivatorIntersection, options);
+    observer.observe(target);
+
+    this._activatorObserver = {
+      unsubscribers,
+      observer
+    };
+  }
+
+  protected _removeActivatorObserver(target: HTMLElement) {
+    this._activatorObserver.observer?.disconnect();
+    this._activatorObserver.observer = undefined;
+    this._activatorObserver.unsubscribers?.forEach((cb) => cb());
+    this._activatorObserver.unsubscribers = [];
   }
 
   protected set _arrowPosition(value: string) {
@@ -93,25 +166,76 @@ export class ESLPopup extends ESLToggleable {
 
     // set arrow position
     if (this.$arrow) {
-      this.$arrow.style.left = `${arrowLeft}px`;
+      this.$arrow.style.left = ['top', 'bottom'].includes(position) ? `${arrowLeft}px` : 'none';
+      this.$arrow.style.top = ['left', 'right'].includes(position) ? `${arrowTop}px` : 'none';
       this._arrowPosition = position;
     }
   }
 
   protected _calculatePosition($activator: HTMLElement) {
-    const {left, arrowLeft} = this._calculateLeft($activator);
-    const {top, arrowTop, position} = this._calculateTop($activator);
+    if (this.position === 'top') {
+      const {left, arrowLeft} = this._calculateLeftT($activator);
+      const {top, arrowTop, position} = this._calculateTopT($activator);
+
+      return {
+        left,
+        top,
+        arrowLeft,
+        arrowTop,
+        position
+      };
+    }
+
+    if (this.position === 'bottom') {
+      const {left, arrowLeft} = this._calculateLeftT($activator);
+      const {top, arrowTop, position} = this._calculateTopB($activator);
+
+      return {
+        left,
+        top,
+        arrowLeft,
+        arrowTop,
+        position
+      };
+    }
+
+    if (this.position === 'left') {
+      const {left, arrowLeft, position} = this._calculateLeftL($activator);
+      const {top, arrowTop} = this._calculateTopH($activator);
+
+      return {
+        left,
+        top,
+        arrowLeft,
+        arrowTop,
+        position
+      };
+    }
+
+    if (this.position === 'right') {
+      const {left, arrowLeft, position} = this._calculateLeftR($activator);
+      const {top, arrowTop} = this._calculateTopH($activator);
+
+      return {
+        left,
+        top,
+        arrowLeft,
+        arrowTop,
+        position
+      };
+    }
 
     return {
-      left,
-      top,
-      arrowLeft,
-      arrowTop,
-      position
+      left: 0,
+      top: 0,
+      arrowLeft: 0,
+      arrowTop: 0,
+      position: 'top'
     };
+
   }
 
-  protected _calculateLeft($activator: HTMLElement) {
+  protected _calculateLeftT($activator: HTMLElement) {
     const triggerRect = $activator.getBoundingClientRect();
     const triggerPosX = triggerRect.left + window.pageXOffset;
     const centerX = triggerPosX + triggerRect.width / 2;
@@ -137,7 +261,7 @@ export class ESLPopup extends ESLToggleable {
     };
   }
 
-  protected _calculateTop($activator: HTMLElement) {
+  protected _calculateTopT($activator: HTMLElement) {
     const arrowRect = this.$arrow ? this.$arrow.getBoundingClientRect() : new DOMRect();
     const triggerRect = $activator.getBoundingClientRect();
     const triggerPosY = triggerRect.top + window.pageYOffset;
@@ -158,4 +282,99 @@ export class ESLPopup extends ESLToggleable {
       position
     };
   }
+
+  protected _calculateTopB($activator: HTMLElement) {
+    const arrowRect = this.$arrow ? this.$arrow.getBoundingClientRect() : new DOMRect();
+    const triggerRect = $activator.getBoundingClientRect();
+    const triggerPosY = triggerRect.top + window.pageYOffset;
+    const arrowHeight = arrowRect.height / 2;
+
+    let arrowTop = triggerPosY + triggerRect.height + this._offsetTrigger;
+    let top = arrowTop + arrowHeight + this._offsetTrigger;
+    const bottom = top + this.offsetHeight;
+    let position = 'bottom';
+    if (this.behavior === 'fit' && this._windowBottom < bottom) {
+      arrowTop = triggerPosY - this._offsetTrigger - arrowHeight;
+      top = arrowTop - this.offsetHeight;
+      position = 'top';
+    }
+
+    return {
+      top,
+      arrowTop,
+      position
+    };
+  }
+
+  protected _calculateLeftL($activator: HTMLElement) {
+    const arrowRect = this.$arrow ? this.$arrow.getBoundingClientRect() : new DOMRect();
+    const triggerRect = $activator.getBoundingClientRect();
+    const triggerLeft = triggerRect.left + window.pageXOffset;
+
+    let arrowLeft = triggerLeft - this._offsetWindow - arrowRect.width / 2;
+    let left = triggerLeft - this._offsetTrigger - arrowRect.width / 2 - this.offsetWidth;
+    let position = 'left';
+
+    if (this.behavior === 'fit' && left < this._offsetWindow) {
+      const triggerRight = triggerRect.right + window.pageXOffset;
+      left = triggerRight + this._offsetTrigger + arrowRect.width / 2;
+      arrowLeft = triggerRight + this._offsetTrigger;
+      position = 'right';
+    }
+
+    return {
+      left,
+      arrowLeft,
+      position
+    };
+  }
+
+  protected _calculateTopH($activator: HTMLElement) {
+    const arrowRect = this.$arrow ? this.$arrow.getBoundingClientRect() : new DOMRect();
+    const triggerRect = $activator.getBoundingClientRect();
+    const triggerTop = triggerRect.top + window.pageYOffset;
+    const triggerCenterY = triggerTop + triggerRect.height / 2;
+    const arrowHeight = arrowRect.height / 2;
+
+    let top = triggerCenterY - this.offsetHeight / 2;
+    let arrowAdjust = 0;
+    if (this.behavior === 'fit' && (top - this._offsetWindow) < window.pageYOffset) {
+      arrowAdjust += window.pageYOffset - (top - this._offsetWindow);
+      top = this._offsetWindow + window.pageYOffset;
+    }
+    if (this.behavior === 'fit' && (top + this.offsetHeight + this._offsetWindow) > this._windowBottom) {
+      arrowAdjust += this._windowBottom - (this.offsetHeight + this._offsetWindow) - top;
+      top = this._windowBottom - (this.offsetHeight + this._offsetWindow);
+    }
+
+    const arrowTop = this.offsetHeight / 2 - arrowHeight - arrowAdjust;
+
+    return {
+      top,
+      arrowTop
+    };
+  }
+
+  protected _calculateLeftR($activator: HTMLElement) {
+    const arrowRect = this.$arrow ? this.$arrow.getBoundingClientRect() : new DOMRect();
+    const triggerRect = $activator.getBoundingClientRect();
+    const triggerRight = triggerRect.right + window.pageXOffset;
+
+    let left = triggerRight + this._offsetTrigger + arrowRect.width / 2;
+    let arrowLeft = triggerRight + this._offsetTrigger;
+    let position = 'right';
+
+    if (this.behavior === 'fit' && (left + this._offsetWindow + this.offsetWidth) > this._windowWidth) {
+      const triggerLeft = triggerRect.left + window.pageXOffset;
+      left = triggerLeft - this._offsetTrigger - arrowRect.width / 2 - this.offsetWidth;
+      arrowLeft = triggerLeft - this._offsetWindow - arrowRect.width / 2;
+      position = 'left';
+    }
+
+    return {
+      left,
+      arrowLeft,
+      position
+    };
+  }
 }
diff --git a/src/modules/esl-popup/core/getComputedStyle.ts b/src/modules/esl-popup/core/getComputedStyle.ts
new file mode 100644
index 000000000..2aad00f6f
--- /dev/null
+++ b/src/modules/esl-popup/core/getComputedStyle.ts
@@ -0,0 +1,5 @@
+import {getWindow} from './getWindow';
+
+export function getComputedStyle(element: Element): CSSStyleDeclaration {
+  return getWindow(element).getComputedStyle(element);
+}
diff --git a/src/modules/esl-popup/core/getDocumentElement.ts b/src/modules/esl-popup/core/getDocumentElement.ts
new file mode 100644
index 000000000..6746fcb55
--- /dev/null
+++ b/src/modules/esl-popup/core/getDocumentElement.ts
@@ -0,0 +1,5 @@
+export function getDocumentElement(element: Element | Window): Element {
+  return ((element instanceof Window
+    ? element.document
+    : element.ownerDocument) || window.document).documentElement;
+}
diff --git a/src/modules/esl-popup/core/getNodeName.ts b/src/modules/esl-popup/core/getNodeName.ts
new file mode 100644
index 000000000..99162d43f
--- /dev/null
+++ b/src/modules/esl-popup/core/getNodeName.ts
@@ -0,0 +1,3 @@
+export function getNodeName(element?: Node | Window): string {
+  return element && !(element instanceof Window)? (element.nodeName).toLowerCase() : '';
+}
diff --git a/src/modules/esl-popup/core/getParentNode.ts b/src/modules/esl-popup/core/getParentNode.ts
new file mode 100644
index 000000000..36ae9c765
--- /dev/null
+++ b/src/modules/esl-popup/core/getParentNode.ts
@@ -0,0 +1,12 @@
+import {getNodeName} from './getNodeName';
+import {getDocumentElement} from './getDocumentElement';
+
+export function getParentNode(element: Element | ShadowRoot): Node {
+  if (getNodeName(element) === 'html') {
+    return element;
+  }
+
+  return (element instanceof ShadowRoot
+    ? element.host
+    : element.assignedSlot || element.parentNode) || getDocumentElement(element as Element);
+}
diff --git a/src/modules/esl-popup/core/getScrollParent.ts b/src/modules/esl-popup/core/getScrollParent.ts
new file mode 100644
index 000000000..13da21461
--- /dev/null
+++ b/src/modules/esl-popup/core/getScrollParent.ts
@@ -0,0 +1,15 @@
+import {getNodeName} from './getNodeName';
+import {isScrollParent} from './isScrollParent';
+import {getParentNode} from './getParentNode';
+
+export function getScrollParent(node: Node): Element {
+  if (['html', 'body', '#document'].indexOf(getNodeName(node)) >= 0) {
+    return node.ownerDocument?.body as Element;
+  }
+
+  if (node instanceof HTMLElement && isScrollParent(node as Element)) {
+    return node as Element;
+  }
+
+  return getScrollParent(getParentNode(node as Element));
+}
diff --git a/src/modules/esl-popup/core/getWindow.ts b/src/modules/esl-popup/core/getWindow.ts
new file mode 100644
index 000000000..6ddaaa085
--- /dev/null
+++ b/src/modules/esl-popup/core/getWindow.ts
@@ -0,0 +1,12 @@
+export function getWindow(node: Node | Window): Window {
+  if (node == null) {
+    return window;
+  }
+
+  if (node instanceof Window) {
+    return node;
+  }
+
+  const ownerDocument = node.ownerDocument;
+  return ownerDocument ? ownerDocument.defaultView || window : window;
+}
diff --git a/src/modules/esl-popup/core/isScrollParent.ts b/src/modules/esl-popup/core/isScrollParent.ts
new file mode 100644
index 000000000..7b5514e19
--- /dev/null
+++ b/src/modules/esl-popup/core/isScrollParent.ts
@@ -0,0 +1,7 @@
+import {getComputedStyle} from './getComputedStyle';
+
+export function isScrollParent(element: Element): boolean {
+  // Firefox wants us to check `-x` and `-y` variations as well
+  const {overflow, overflowX, overflowY} = getComputedStyle(element);
+  return /auto|scroll|overlay|hidden/.test(overflow + overflowY + overflowX);
+}
diff --git a/src/modules/esl-popup/core/listScrollParents.ts b/src/modules/esl-popup/core/listScrollParents.ts
new file mode 100644
index 000000000..256929b0f
--- /dev/null
+++ b/src/modules/esl-popup/core/listScrollParents.ts
@@ -0,0 +1,22 @@
+import {getScrollParent} from './getScrollParent';
+import {getParentNode} from './getParentNode';
+import {isScrollParent} from './isScrollParent';
+
+/*
+given a DOM element, return the list of all scroll parents, up the list of ancesors
+until we get to the top window object. This list is what we attach scroll listeners
+to, because if any of these parent elements scroll, we'll need to re-calculate the
+reference element's position.
+*/
+export function listScrollParents(element: Node, list: Element[] = []): Element[] {
+  const scrollParent = getScrollParent(element);
+  const isBody = scrollParent === element.ownerDocument?.body;
+  const target = isBody
+    ? isScrollParent(scrollParent) ? scrollParent : []
+    : scrollParent;
+
+  const updatedList = list.concat(target);
+  return isBody
+    ? updatedList
+    : updatedList.concat(listScrollParents(getParentNode(scrollParent)));
+}