diff --git a/src/display/operations.js b/src/display/operations.js
index b004575b..ca5d3f61 100644
--- a/src/display/operations.js
+++ b/src/display/operations.js
@@ -2,7 +2,7 @@ import { clipPos } from "../line/pos.js"
 import { findMaxLine } from "../line/spans.js"
 import { displayWidth, measureChar, scrollGap } from "../measurement/position_measurement.js"
 import { signal } from "../util/event.js"
-import { activeElt, doc } from "../util/dom.js"
+import { activeElt, rootNode } from "../util/dom.js"
 import { finishOperation, pushOperation } from "../util/operation_group.js"
 
 import { ensureFocus } from "./focus.js"
@@ -116,7 +116,7 @@ function endOperation_W2(op) {
     cm.display.maxLineChanged = false
   }
 
-  let takeFocus = op.focus && op.focus == activeElt(doc(cm))
+  let takeFocus = op.focus && op.focus == activeElt(rootNode(cm))
   if (op.preparedSelection)
     cm.display.input.showSelection(op.preparedSelection, takeFocus)
   if (op.updatedDisplay || op.startHeight != cm.doc.height)
diff --git a/src/display/update_display.js b/src/display/update_display.js
index 63529d51..23428c88 100644
--- a/src/display/update_display.js
+++ b/src/display/update_display.js
@@ -3,7 +3,7 @@ import { heightAtLine, visualLineEndNo, visualLineNo } from "../line/spans.js"
 import { getLine, lineNumberFor } from "../line/utils_line.js"
 import { displayHeight, displayWidth, getDimensions, paddingVert, scrollGap } from "../measurement/position_measurement.js"
 import { mac, webkit } from "../util/browser.js"
-import { activeElt, removeChildren, contains, win, doc } from "../util/dom.js"
+import { activeElt, removeChildren, contains, win, rootNode } from "../util/dom.js"
 import { hasHandler, signal } from "../util/event.js"
 import { signalLater } from "../util/operation_group.js"
 import { indexOf } from "../util/misc.js"
@@ -57,7 +57,7 @@ export function maybeClipScrollbars(cm) {
 
 function selectionSnapshot(cm) {
   if (cm.hasFocus()) return null
-  let active = activeElt(doc(cm))
+  let active = activeElt(rootNode(cm))
   if (!active || !contains(cm.display.lineDiv, active)) return null
   let result = {activeElt: active}
   if (window.getSelection) {
@@ -73,7 +73,7 @@ function selectionSnapshot(cm) {
 }
 
 function restoreSelection(snapshot) {
-  if (!snapshot || !snapshot.activeElt || snapshot.activeElt == activeElt(snapshot.activeElt.ownerDocument)) return
+  if (!snapshot || !snapshot.activeElt || snapshot.activeElt == activeElt(snapshot.activeElt.getRootNode())) return
   snapshot.activeElt.focus()
   if (!/^(INPUT|TEXTAREA)$/.test(snapshot.activeElt.nodeName) &&
       snapshot.anchorNode && contains(document.body, snapshot.anchorNode) && contains(document.body, snapshot.focusNode)) {
diff --git a/src/edit/fromTextArea.js b/src/edit/fromTextArea.js
index cdd10d74..a13e3595 100644
--- a/src/edit/fromTextArea.js
+++ b/src/edit/fromTextArea.js
@@ -13,7 +13,7 @@ export function fromTextArea(textarea, options) {
   // Set autofocus to true if this textarea is focused, or if it has
   // autofocus and no other element is focused.
   if (options.autofocus == null) {
-    let hasFocus = activeElt(textarea.ownerDocument)
+    let hasFocus = activeElt(textarea.getRootNode())
     options.autofocus = hasFocus == textarea ||
       textarea.getAttribute("autofocus") != null && hasFocus == document.body
   }
diff --git a/src/edit/key_events.js b/src/edit/key_events.js
index 1d3c9f90..1283663d 100644
--- a/src/edit/key_events.js
+++ b/src/edit/key_events.js
@@ -3,7 +3,7 @@ import { restartBlink } from "../display/selection.js"
 import { isModifierKey, keyName, lookupKey } from "../input/keymap.js"
 import { eventInWidget } from "../measurement/widgets.js"
 import { ie, ie_version, mac, presto, gecko } from "../util/browser.js"
-import { activeElt, addClass, rmClass, doc } from "../util/dom.js"
+import { activeElt, addClass, rmClass, rootNode } from "../util/dom.js"
 import { e_preventDefault, off, on, signalDOMEvent } from "../util/event.js"
 import { hasCopyEvent } from "../util/feature_detection.js"
 import { Delayed, Pass } from "../util/misc.js"
@@ -107,7 +107,7 @@ let lastStoppedKey = null
 export function onKeyDown(e) {
   let cm = this
   if (e.target && e.target != cm.display.input.getField()) return
-  cm.curOp.focus = activeElt(doc(cm))
+  cm.curOp.focus = activeElt(rootNode(cm))
   if (signalDOMEvent(cm, e)) return
   // IE does strange things with escape.
   if (ie && ie_version < 11 && e.keyCode == 27) e.returnValue = false
diff --git a/src/edit/methods.js b/src/edit/methods.js
index b1cbcc9e..0acef25b 100644
--- a/src/edit/methods.js
+++ b/src/edit/methods.js
@@ -1,7 +1,7 @@
 import { deleteNearSelection } from "./deleteNearSelection.js"
 import { commands } from "./commands.js"
 import { attachDoc } from "../model/document_data.js"
-import { activeElt, addClass, rmClass, doc, win } from "../util/dom.js"
+import { activeElt, addClass, rmClass, rootNode, win } from "../util/dom.js"
 import { eventMixin, signal } from "../util/event.js"
 import { getLineStyles, getContextBefore, takeToken } from "../line/highlight.js"
 import { indentLine } from "../input/indent.js"
@@ -358,7 +358,7 @@ export default function(CodeMirror) {
 
       signal(this, "overwriteToggle", this, this.state.overwrite)
     },
-    hasFocus: function() { return this.display.input.getField() == activeElt(doc(this)) },
+    hasFocus: function() { return this.display.input.getField() == activeElt(rootNode(this)) },
     isReadOnly: function() { return !!(this.options.readOnly || this.doc.cantEdit) },
 
     scrollTo: methodOp(function (x, y) { scrollToCoords(this, x, y) }),
diff --git a/src/edit/mouse_events.js b/src/edit/mouse_events.js
index e854d647..94f98034 100644
--- a/src/edit/mouse_events.js
+++ b/src/edit/mouse_events.js
@@ -9,7 +9,7 @@ import { normalizeSelection, Range, Selection } from "../model/selection.js"
 import { extendRange, extendSelection, replaceOneSelection, setSelection } from "../model/selection_updates.js"
 import { captureRightClick, chromeOS, ie, ie_version, mac, webkit, safari } from "../util/browser.js"
 import { getOrder, getBidiPartAt } from "../util/bidi.js"
-import { activeElt, doc as getDoc, win } from "../util/dom.js"
+import { activeElt, rootNode, win } from "../util/dom.js"
 import { e_button, e_defaultPrevented, e_preventDefault, e_target, hasHandler, off, on, signal, signalDOMEvent } from "../util/event.js"
 import { dragAndDrop } from "../util/feature_detection.js"
 import { bind, countColumn, findColumn, sel_mouse } from "../util/misc.js"
@@ -128,7 +128,7 @@ function configureMouse(cm, repeat, event) {
 
 function leftButtonDown(cm, pos, repeat, event) {
   if (ie) setTimeout(bind(ensureFocus, cm), 0)
-  else cm.curOp.focus = activeElt(getDoc(cm))
+  else cm.curOp.focus = activeElt(rootNode(cm))
 
   let behavior = configureMouse(cm, repeat, event)
 
@@ -292,7 +292,7 @@ function leftButtonSelect(cm, event, start, behavior) {
     let cur = posFromMouse(cm, e, true, behavior.unit == "rectangle")
     if (!cur) return
     if (cmp(cur, lastPos) != 0) {
-      cm.curOp.focus = activeElt(getDoc(cm))
+      cm.curOp.focus = activeElt(rootNode(cm))
       extendTo(cur)
       let visible = visibleLines(display, doc)
       if (cur.line >= visible.to || cur.line < visible.from)
diff --git a/src/input/ContentEditableInput.js b/src/input/ContentEditableInput.js
index f789af74..b1f97af4 100644
--- a/src/input/ContentEditableInput.js
+++ b/src/input/ContentEditableInput.js
@@ -97,7 +97,7 @@ export default class ContentEditableInput {
       disableBrowserMagic(te)
       cm.display.lineSpace.insertBefore(kludge, cm.display.lineSpace.firstChild)
       te.value = lastCopied.text.join("\n")
-      let hadFocus = activeElt(div.ownerDocument)
+      let hadFocus = activeElt(div.getRootNode())
       selectInput(te)
       setTimeout(() => {
         cm.display.lineSpace.removeChild(kludge)
@@ -120,7 +120,7 @@ export default class ContentEditableInput {
 
   prepareSelection() {
     let result = prepareSelection(this.cm, false)
-    result.focus = activeElt(this.div.ownerDocument) == this.div
+    result.focus = activeElt(this.div.getRootNode()) == this.div
     return result
   }
 
@@ -214,7 +214,7 @@ export default class ContentEditableInput {
 
   focus() {
     if (this.cm.options.readOnly != "nocursor") {
-      if (!this.selectionInEditor() || activeElt(this.div.ownerDocument) != this.div)
+      if (!this.selectionInEditor() || activeElt(this.div.getRootNode()) != this.div)
         this.showSelection(this.prepareSelection(), true)
       this.div.focus()
     }
diff --git a/src/input/TextareaInput.js b/src/input/TextareaInput.js
index 0aac125b..07ef6cac 100644
--- a/src/input/TextareaInput.js
+++ b/src/input/TextareaInput.js
@@ -182,7 +182,7 @@ export default class TextareaInput {
   supportsTouch() { return false }
 
   focus() {
-    if (this.cm.options.readOnly != "nocursor" && (!mobile || activeElt(this.textarea.ownerDocument) != this.textarea)) {
+    if (this.cm.options.readOnly != "nocursor" && (!mobile || activeElt(this.textarea.getRootNode()) != this.textarea)) {
       try { this.textarea.focus() }
       catch (e) {} // IE8 will throw if the textarea is display: none or not in DOM
     }
diff --git a/src/util/dom.js b/src/util/dom.js
index 6672645a..89fbb1a1 100644
--- a/src/util/dom.js
+++ b/src/util/dom.js
@@ -64,10 +64,13 @@ export function contains(parent, child) {
   } while (child = child.parentNode)
 }
 
-export function activeElt(doc) {
+export function activeElt(rootNode) {
   // IE and Edge may throw an "Unspecified Error" when accessing document.activeElement.
   // IE < 10 will throw when accessed while the page is loading or in an iframe.
   // IE > 9 and Edge will throw when accessed in an iframe if document.body is unavailable.
+  return rootNode.activeElement;
+
+/*
   let activeElement
   try {
     activeElement = doc.activeElement
@@ -77,6 +80,7 @@ export function activeElt(doc) {
   while (activeElement && activeElement.shadowRoot && activeElement.shadowRoot.activeElement)
     activeElement = activeElement.shadowRoot.activeElement
   return activeElement
+*/
 }
 
 export function addClass(node, cls) {
@@ -98,4 +102,6 @@ else if (ie) // Suppress mysterious IE10 errors
 
 export function doc(cm) { return cm.display.wrapper.ownerDocument }
 
+export function rootNode(cm) { return cm.display.wrapper.getRootNode() }
+
 export function win(cm) { return doc(cm).defaultView }