diff --git a/services/web/.babelrc b/services/web/.babelrc
index d2b230bb27..d354026e94 100644
--- a/services/web/.babelrc
+++ b/services/web/.babelrc
@@ -7,14 +7,18 @@
     }]
   ],
   "plugins": ["angularjs-annotate"],
-  // Disable core-js polyfilling in test environment, to prevent interference
-  // with mocking
+  // Target our current Node version in test environment, to transform and
+  // polyfill only what's necessary
   "env": {
     "test": {
       "presets": [
         "@babel/react",
-        "@babel/env"
+        ["@babel/env", {
+            "targets": {"node": "10.21"},
+            "useBuiltIns": "usage",
+            "corejs": { "version": 3 }
+          }]
       ]
     }
   }
-}
\ No newline at end of file
+}
diff --git a/services/web/frontend/extracted-translation-keys.json b/services/web/frontend/extracted-translation-keys.json
index 4faef59296..35f8a2d908 100644
--- a/services/web/frontend/extracted-translation-keys.json
+++ b/services/web/frontend/extracted-translation-keys.json
@@ -2,5 +2,7 @@
   "file_outline",
   "the_file_outline_is_a_new_feature_click_the_icon_to_learn_more",
   "we_cant_find_any_sections_or_subsections_in_this_file",
-  "find_out_more_about_the_file_outline"
+  "find_out_more_about_the_file_outline",
+  "expand",
+  "collapse"
 ]
diff --git a/services/web/frontend/js/features/outline/components/outline-item.js b/services/web/frontend/js/features/outline/components/outline-item.js
index fb775b33c9..4749121a8c 100644
--- a/services/web/frontend/js/features/outline/components/outline-item.js
+++ b/services/web/frontend/js/features/outline/components/outline-item.js
@@ -2,6 +2,7 @@ import React, { useState, useEffect, createRef, useRef } from 'react'
 import PropTypes from 'prop-types'
 import scrollIntoViewIfNeeded from 'scroll-into-view-if-needed'
 import classNames from 'classnames'
+import { useTranslation } from 'react-i18next'
 import OutlineList from './outline-list'
 
 function getChildrenLines(children) {
@@ -13,6 +14,8 @@ function getChildrenLines(children) {
 }
 
 function OutlineItem({ outlineItem, jumpToLine, highlightedLine }) {
+  const { t } = useTranslation()
+
   const [expanded, setExpanded] = useState(true)
   const titleElementRef = createRef()
   const isHighlightedRef = useRef(false)
@@ -30,9 +33,11 @@ function OutlineItem({ outlineItem, jumpToLine, highlightedLine }) {
     !expanded &&
     getChildrenLines(outlineItem.children).includes(highlightedLine)
 
+  const isHighlighted =
+    highlightedLine === outlineItem.line || hasHighlightedChild
+
   const itemLinkClasses = classNames('outline-item-link', {
-    'outline-item-link-highlight':
-      highlightedLine === outlineItem.line || hasHighlightedChild
+    'outline-item-link-highlight': isHighlighted
   })
 
   function handleExpandCollapseClick() {
@@ -64,13 +69,23 @@ function OutlineItem({ outlineItem, jumpToLine, highlightedLine }) {
     [highlightedLine, titleElementRef, isHighlightedRef]
   )
 
+  // don't set the aria-expanded attribute when there are no children
+  const ariaExpandedValue = outlineItem.children ? expanded : undefined
+
   return (
-    <li className={mainItemClasses}>
+    <li
+      className={mainItemClasses}
+      aria-expanded={ariaExpandedValue}
+      role="treeitem"
+      aria-current={isHighlighted}
+      aria-label={outlineItem.title}
+    >
       <div className="outline-item-row">
         {outlineItem.children ? (
           <button
             className="outline-item-expand-collapse-btn"
             onClick={handleExpandCollapseClick}
+            aria-label={expanded ? t('collapse') : t('expand')}
           >
             <i className={expandCollapseIconClasses} />
           </button>
@@ -100,7 +115,7 @@ OutlineItem.propTypes = {
   outlineItem: PropTypes.exact({
     line: PropTypes.number.isRequired,
     title: PropTypes.string.isRequired,
-    level: PropTypes.number.isRequired,
+    level: PropTypes.number,
     children: PropTypes.array
   }).isRequired,
   jumpToLine: PropTypes.func.isRequired,
diff --git a/services/web/frontend/js/features/outline/components/outline-list.js b/services/web/frontend/js/features/outline/components/outline-list.js
index f6f5efa9b0..2380846455 100644
--- a/services/web/frontend/js/features/outline/components/outline-list.js
+++ b/services/web/frontend/js/features/outline/components/outline-list.js
@@ -8,7 +8,7 @@ function OutlineList({ outline, jumpToLine, isRoot, highlightedLine }) {
     'outline-item-list-root': isRoot
   })
   return (
-    <ul className={listClasses}>
+    <ul className={listClasses} role={isRoot ? 'tree' : 'group'}>
       {outline.map((outlineItem, idx) => {
         return (
           <OutlineItem
diff --git a/services/web/test/frontend/bootstrap.js b/services/web/test/frontend/bootstrap.js
index ea312f97a6..c66435efb0 100644
--- a/services/web/test/frontend/bootstrap.js
+++ b/services/web/test/frontend/bootstrap.js
@@ -8,3 +8,6 @@ require('jsdom-global/register')
 // has a nicer failure messages
 const chai = require('chai')
 chai.use(require('sinon-chai'))
+
+window.i18n = { currentLangCode: 'en' }
+require('../../frontend/js/i18n')
diff --git a/services/web/test/frontend/features/outline/components/outline-item.test.js b/services/web/test/frontend/features/outline/components/outline-item.test.js
new file mode 100644
index 0000000000..6c5f508745
--- /dev/null
+++ b/services/web/test/frontend/features/outline/components/outline-item.test.js
@@ -0,0 +1,112 @@
+import { expect } from 'chai'
+import React from 'react'
+import sinon from 'sinon'
+import { screen, render, fireEvent } from '@testing-library/react'
+
+import OutlineItem from '../../../../../frontend/js/features/outline/components/outline-item'
+
+describe('<OutlineItem />', function() {
+  before(function() {
+    this.jumpToLine = sinon.stub()
+  })
+
+  afterEach(function() {
+    this.jumpToLine.reset()
+  })
+
+  it('renders basic item', function() {
+    const outlineItem = {
+      title: 'Test Title',
+      line: 1
+    }
+    render(
+      <OutlineItem outlineItem={outlineItem} jumpToLine={this.jumpToLine} />
+    )
+
+    screen.getByRole('treeitem', { current: false })
+    screen.getByRole('button', { name: outlineItem.title })
+    expect(screen.queryByRole('button', { name: 'Collapse' })).to.not.exist
+  })
+
+  it('collapses and expands', function() {
+    const outlineItem = {
+      title: 'Parent',
+      line: 1,
+      children: [{ title: 'Child', line: 2 }]
+    }
+    render(
+      <OutlineItem outlineItem={outlineItem} jumpToLine={this.jumpToLine} />
+    )
+
+    const collapseButton = screen.getByRole('button', { name: 'Collapse' })
+
+    // test that children are rendered
+    screen.getByRole('button', { name: 'Child' })
+
+    fireEvent.click(collapseButton)
+
+    screen.getByRole('button', { name: 'Expand' })
+
+    expect(screen.queryByRole('button', { name: 'Child' })).to.not.exist
+  })
+
+  it('highlights', function() {
+    const outlineItem = {
+      title: 'Parent',
+      line: 1
+    }
+
+    render(
+      <OutlineItem
+        outlineItem={outlineItem}
+        jumpToLine={this.jumpToLine}
+        highlightedLine={1}
+      />
+    )
+
+    screen.getByRole('treeitem', { current: true })
+  })
+
+  it('highlights when has collapsed highlighted child', function() {
+    const outlineItem = {
+      title: 'Parent',
+      line: 1,
+      children: [{ title: 'Child', line: 2 }]
+    }
+    render(
+      <OutlineItem
+        outlineItem={outlineItem}
+        jumpToLine={this.jumpToLine}
+        highlightedLine={2}
+      />
+    )
+
+    screen.getByRole('treeitem', { name: 'Parent', current: false })
+    screen.getByRole('treeitem', { name: 'Child', current: true })
+
+    fireEvent.click(screen.getByRole('button', { name: 'Collapse' }))
+
+    screen.getByRole('treeitem', { name: 'Parent', current: true })
+  })
+
+  it('click and double-click jump to location', function() {
+    const outlineItem = {
+      title: 'Parent',
+      line: 1
+    }
+    render(
+      <OutlineItem outlineItem={outlineItem} jumpToLine={this.jumpToLine} />
+    )
+
+    const titleButton = screen.getByRole('button', { name: outlineItem.title })
+
+    fireEvent.click(titleButton)
+    sinon.assert.calledOnce(this.jumpToLine)
+    sinon.assert.calledWith(this.jumpToLine, 1, false)
+
+    this.jumpToLine.reset()
+    fireEvent.doubleClick(titleButton)
+    sinon.assert.calledOnce(this.jumpToLine)
+    sinon.assert.calledWith(this.jumpToLine, 1, true)
+  })
+})