From f95c28f9a7ec3e13f30fff47f03d6cd21ff52e1c Mon Sep 17 00:00:00 2001
From: "Henri F." <henrif75@users.noreply.github.com>
Date: Wed, 15 Jan 2025 19:11:19 -0800
Subject: [PATCH] Fix a few accessibility violations (#2547)

* Add chrome.css and general.css to override default css file. This is
necessary to fix links without underline (hyperlinks relying only on
color).
* Fix pop-out button without id and wrong ARIA-ROLE
* Speaker's notes now at correct heading sequence (H3)
---
 theme/css/chrome.css        | 681 ++++++++++++++++++++++++++++++++++++
 theme/css/general.css       | 279 +++++++++++++++
 theme/css/speaker-notes.css |   5 +-
 theme/index.hbs             |   1 -
 theme/speaker-notes.js      |  12 +-
 5 files changed, 970 insertions(+), 8 deletions(-)
 create mode 100644 theme/css/chrome.css
 create mode 100644 theme/css/general.css

diff --git a/theme/css/chrome.css b/theme/css/chrome.css
new file mode 100644
index 00000000..cad7d5f4
--- /dev/null
+++ b/theme/css/chrome.css
@@ -0,0 +1,681 @@
+/* CSS for UI elements (a.k.a. chrome) */
+
+html {
+  scrollbar-color: var(--scrollbar) var(--bg);
+}
+#searchresults a,
+.content a:link,
+a:visited,
+a > .hljs {
+  color: var(--links);
+}
+
+/*
+    body-container is necessary because mobile browsers don't seem to like
+    overflow-x on the body tag when there is a <meta name="viewport"> tag.
+*/
+#body-container {
+  /*
+        This is used when the sidebar pushes the body content off the side of
+        the screen on small screens. Without it, dragging on mobile Safari
+        will want to reposition the viewport in a weird way.
+    */
+  overflow-x: clip;
+}
+
+/* Menu Bar */
+
+#menu-bar,
+#menu-bar-hover-placeholder {
+  z-index: 101;
+  margin: auto calc(0px - var(--page-padding));
+}
+#menu-bar {
+  position: relative;
+  display: flex;
+  flex-wrap: wrap;
+  background-color: var(--bg);
+  border-block-end-color: var(--bg);
+  border-block-end-width: 1px;
+  border-block-end-style: solid;
+}
+#menu-bar.sticky,
+#menu-bar-hover-placeholder:hover + #menu-bar,
+#menu-bar:hover,
+html.sidebar-visible #menu-bar {
+  position: -webkit-sticky;
+  position: sticky;
+  top: 0 !important;
+}
+#menu-bar-hover-placeholder {
+  position: sticky;
+  position: -webkit-sticky;
+  top: 0;
+  height: var(--menu-bar-height);
+}
+#menu-bar.bordered {
+  border-block-end-color: var(--table-border-color);
+}
+#menu-bar i,
+#menu-bar .icon-button {
+  position: relative;
+  padding: 0 8px;
+  z-index: 10;
+  line-height: var(--menu-bar-height);
+  cursor: pointer;
+  transition: color 0.5s;
+}
+@media only screen and (max-width: 420px) {
+  #menu-bar i,
+  #menu-bar .icon-button {
+    padding: 0 5px;
+  }
+}
+
+.icon-button {
+  border: none;
+  background: none;
+  padding: 0;
+  color: inherit;
+}
+.icon-button i {
+  margin: 0;
+}
+
+.right-buttons {
+  margin: 0 15px;
+}
+.right-buttons a {
+  text-decoration: none;
+}
+
+.left-buttons {
+  display: flex;
+  margin: 0 5px;
+}
+html:not(.js) .left-buttons button {
+  display: none;
+}
+
+.menu-title {
+  display: inline-block;
+  font-weight: 200;
+  font-size: 2.4rem;
+  line-height: var(--menu-bar-height);
+  text-align: center;
+  margin: 0;
+  flex: 1;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+.menu-title {
+  cursor: pointer;
+}
+
+.menu-bar,
+.menu-bar:visited,
+.nav-chapters,
+.nav-chapters:visited,
+.mobile-nav-chapters,
+.mobile-nav-chapters:visited,
+.menu-bar .icon-button,
+.menu-bar a i {
+  color: var(--icons);
+}
+
+.menu-bar i:hover,
+.menu-bar .icon-button:hover,
+.nav-chapters:hover,
+.mobile-nav-chapters i:hover {
+  color: var(--icons-hover);
+}
+
+/* Nav Icons */
+
+.nav-chapters {
+  font-size: 2.5em;
+  text-align: center;
+  text-decoration: none;
+
+  position: fixed;
+  top: 0;
+  bottom: 0;
+  margin: 0;
+  max-width: 150px;
+  min-width: 90px;
+
+  display: flex;
+  justify-content: center;
+  align-content: center;
+  flex-direction: column;
+
+  transition: color 0.5s, background-color 0.5s;
+}
+
+.nav-chapters:hover {
+  text-decoration: none;
+  background-color: var(--theme-hover);
+  transition: background-color 0.15s, color 0.15s;
+}
+
+.nav-wrapper {
+  margin-block-start: 50px;
+  display: none;
+}
+
+.mobile-nav-chapters {
+  font-size: 2.5em;
+  text-align: center;
+  text-decoration: none;
+  width: 90px;
+  border-radius: 5px;
+  background-color: var(--sidebar-bg);
+}
+
+/* Only Firefox supports flow-relative values */
+.previous {
+  float: left;
+}
+[dir="rtl"] .previous {
+  float: right;
+}
+
+/* Only Firefox supports flow-relative values */
+.next {
+  float: right;
+  right: var(--page-padding);
+}
+[dir="rtl"] .next {
+  float: left;
+  right: unset;
+  left: var(--page-padding);
+}
+
+/* Use the correct buttons for RTL layouts*/
+[dir="rtl"] .previous i.fa-angle-left:before {
+  content: "\f105";
+}
+[dir="rtl"] .next i.fa-angle-right:before {
+  content: "\f104";
+}
+
+@media only screen and (max-width: 1080px) {
+  .nav-wide-wrapper {
+    display: none;
+  }
+  .nav-wrapper {
+    display: block;
+  }
+}
+
+/* sidebar-visible */
+@media only screen and (max-width: 1380px) {
+  #sidebar-toggle-anchor:checked ~ .page-wrapper .nav-wide-wrapper {
+    display: none;
+  }
+  #sidebar-toggle-anchor:checked ~ .page-wrapper .nav-wrapper {
+    display: block;
+  }
+}
+
+/* Inline code */
+
+:not(pre) > .hljs {
+  display: inline;
+  padding: 0.1em 0.3em;
+  border-radius: 3px;
+}
+
+:not(pre):not(a) > .hljs {
+  color: var(--inline-code-color);
+  overflow-x: initial;
+}
+
+a:hover > .hljs {
+  text-decoration: underline;
+}
+
+pre {
+  position: relative;
+}
+pre > .buttons {
+  position: absolute;
+  z-index: 100;
+  right: 0px;
+  top: 2px;
+  margin: 0px;
+  padding: 2px 0px;
+
+  color: var(--sidebar-fg);
+  cursor: pointer;
+  visibility: hidden;
+  opacity: 0;
+  transition: visibility 0.1s linear, opacity 0.1s linear;
+}
+pre:hover > .buttons {
+  visibility: visible;
+  opacity: 1;
+}
+pre > .buttons :hover {
+  color: var(--sidebar-active);
+  border-color: var(--icons-hover);
+  background-color: var(--theme-hover);
+}
+pre > .buttons i {
+  margin-inline-start: 8px;
+}
+pre > .buttons button {
+  cursor: inherit;
+  margin: 0px 5px;
+  padding: 4px 4px 3px 5px;
+  font-size: 23px;
+
+  border-style: solid;
+  border-width: 1px;
+  border-radius: 4px;
+  border-color: var(--icons);
+  background-color: var(--theme-popup-bg);
+  transition: 100ms;
+  transition-property: color, border-color, background-color;
+  color: var(--icons);
+}
+
+pre > .buttons button.clip-button {
+  padding: 2px 4px 0px 6px;
+}
+pre > .buttons button.clip-button::before {
+  /* clipboard image from octicons (https://github.com/primer/octicons/tree/v2.0.0) MIT license
+     */
+  content: url('data:image/svg+xml,<svg width="21" height="20" viewBox="0 0 24 25" \
+xmlns="http://www.w3.org/2000/svg" aria-label="Copy to clipboard">\
+<path d="M18 20h2v3c0 1-1 2-2 2H2c-.998 0-2-1-2-2V5c0-.911.755-1.667 1.667-1.667h5A3.323 3.323 0 \
+0110 0a3.323 3.323 0 013.333 3.333h5C19.245 3.333 20 4.09 20 5v8.333h-2V9H2v14h16v-3zM3 \
+7h14c0-.911-.793-1.667-1.75-1.667H13.5c-.957 0-1.75-.755-1.75-1.666C11.75 2.755 10.957 2 10 \
+2s-1.75.755-1.75 1.667c0 .911-.793 1.666-1.75 1.666H4.75C3.793 5.333 3 6.09 3 7z"/>\
+<path d="M4 19h6v2H4zM12 11H4v2h8zM4 17h4v-2H4zM15 15v-3l-4.5 4.5L15 21v-3l8.027-.032L23 15z"/>\
+</svg>');
+  filter: var(--copy-button-filter);
+}
+pre > .buttons button.clip-button:hover::before {
+  filter: var(--copy-button-filter-hover);
+}
+
+@media (pointer: coarse) {
+  pre > .buttons button {
+    /* On mobile, make it easier to tap buttons. */
+    padding: 0.3rem 1rem;
+  }
+
+  .sidebar-resize-indicator {
+    /* Hide resize indicator on devices with limited accuracy */
+    display: none;
+  }
+}
+pre > code {
+  display: block;
+  padding: 1rem;
+}
+
+/* FIXME: ACE editors overlap their buttons because ACE does absolute
+   positioning within the code block which breaks padding. The only solution I
+   can think of is to move the padding to the outer pre tag (or insert a div
+   wrapper), but that would require fixing a whole bunch of CSS rules.
+*/
+.hljs.ace_editor {
+  padding: 0rem 0rem;
+}
+
+pre > .result {
+  margin-block-start: 10px;
+}
+
+/* Search */
+
+#searchresults a {
+  text-decoration: none;
+}
+
+mark {
+  border-radius: 2px;
+  padding-block-start: 0;
+  padding-block-end: 1px;
+  padding-inline-start: 3px;
+  padding-inline-end: 3px;
+  margin-block-start: 0;
+  margin-block-end: -1px;
+  margin-inline-start: -3px;
+  margin-inline-end: -3px;
+  background-color: var(--search-mark-bg);
+  transition: background-color 300ms linear;
+  cursor: pointer;
+}
+
+mark.fade-out {
+  background-color: rgba(0, 0, 0, 0) !important;
+  cursor: auto;
+}
+
+.searchbar-outer {
+  margin-inline-start: auto;
+  margin-inline-end: auto;
+  max-width: var(--content-max-width);
+}
+
+#searchbar {
+  width: 100%;
+  margin-block-start: 5px;
+  margin-block-end: 0;
+  margin-inline-start: auto;
+  margin-inline-end: auto;
+  padding: 10px 16px;
+  transition: box-shadow 300ms ease-in-out;
+  border: 1px solid var(--searchbar-border-color);
+  border-radius: 3px;
+  background-color: var(--searchbar-bg);
+  color: var(--searchbar-fg);
+}
+#searchbar:focus,
+#searchbar.active {
+  box-shadow: 0 0 3px var(--searchbar-shadow-color);
+}
+
+.searchresults-header {
+  font-weight: bold;
+  font-size: 1em;
+  padding-block-start: 18px;
+  padding-block-end: 0;
+  padding-inline-start: 5px;
+  padding-inline-end: 0;
+  color: var(--searchresults-header-fg);
+}
+
+.searchresults-outer {
+  margin-inline-start: auto;
+  margin-inline-end: auto;
+  max-width: var(--content-max-width);
+  border-block-end: 1px dashed var(--searchresults-border-color);
+}
+
+ul#searchresults {
+  list-style: none;
+  padding-inline-start: 20px;
+}
+ul#searchresults li {
+  margin: 10px 0px;
+  padding: 2px;
+  border-radius: 2px;
+}
+ul#searchresults li.focus {
+  background-color: var(--searchresults-li-bg);
+}
+ul#searchresults span.teaser {
+  display: block;
+  clear: both;
+  margin-block-start: 5px;
+  margin-block-end: 0;
+  margin-inline-start: 20px;
+  margin-inline-end: 0;
+  font-size: 0.8em;
+}
+ul#searchresults span.teaser em {
+  font-weight: bold;
+  font-style: normal;
+}
+
+/* Sidebar */
+
+.sidebar {
+  position: fixed;
+  left: 0;
+  top: 0;
+  bottom: 0;
+  width: var(--sidebar-width);
+  font-size: 0.875em;
+  box-sizing: border-box;
+  -webkit-overflow-scrolling: touch;
+  overscroll-behavior-y: contain;
+  background-color: var(--sidebar-bg);
+  color: var(--sidebar-fg);
+}
+.sidebar-iframe-inner {
+  background-color: var(--sidebar-bg);
+  color: var(--sidebar-fg);
+  padding: 10px 10px;
+  margin: 0;
+  font-size: 1.4rem;
+}
+.sidebar-iframe-outer {
+  border: none;
+  height: 100%;
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  left: 0;
+  right: 0;
+}
+[dir="rtl"] .sidebar {
+  left: unset;
+  right: 0;
+}
+.sidebar-resizing {
+  -moz-user-select: none;
+  -webkit-user-select: none;
+  -ms-user-select: none;
+  user-select: none;
+}
+html:not(.sidebar-resizing) .sidebar {
+  transition: transform 0.3s; /* Animation: slide away */
+}
+.sidebar code {
+  line-height: 2em;
+}
+.sidebar .sidebar-scrollbox {
+  overflow-y: auto;
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  left: 0;
+  right: 0;
+  padding: 10px 10px;
+}
+.sidebar .sidebar-resize-handle {
+  position: absolute;
+  cursor: col-resize;
+  width: 0;
+  right: calc(var(--sidebar-resize-indicator-width) * -1);
+  top: 0;
+  bottom: 0;
+  display: flex;
+  align-items: center;
+}
+
+.sidebar-resize-handle .sidebar-resize-indicator {
+  width: 100%;
+  height: 12px;
+  background-color: var(--icons);
+  margin-inline-start: var(--sidebar-resize-indicator-space);
+}
+
+[dir="rtl"] .sidebar .sidebar-resize-handle {
+  left: calc(var(--sidebar-resize-indicator-width) * -1);
+  right: unset;
+}
+.js .sidebar .sidebar-resize-handle {
+  cursor: col-resize;
+  width: calc(
+    var(--sidebar-resize-indicator-width) -
+      var(--sidebar-resize-indicator-space)
+  );
+}
+/* sidebar-hidden */
+#sidebar-toggle-anchor:not(:checked) ~ .sidebar {
+  transform: translateX(
+    calc(0px - var(--sidebar-width) - var(--sidebar-resize-indicator-width))
+  );
+  z-index: -1;
+}
+[dir="rtl"] #sidebar-toggle-anchor:not(:checked) ~ .sidebar {
+  transform: translateX(
+    calc(var(--sidebar-width) + var(--sidebar-resize-indicator-width))
+  );
+}
+.sidebar::-webkit-scrollbar {
+  background: var(--sidebar-bg);
+}
+.sidebar::-webkit-scrollbar-thumb {
+  background: var(--scrollbar);
+}
+
+/* sidebar-visible */
+#sidebar-toggle-anchor:checked ~ .page-wrapper {
+  transform: translateX(
+    calc(var(--sidebar-width) + var(--sidebar-resize-indicator-width))
+  );
+}
+[dir="rtl"] #sidebar-toggle-anchor:checked ~ .page-wrapper {
+  transform: translateX(
+    calc(0px - var(--sidebar-width) - var(--sidebar-resize-indicator-width))
+  );
+}
+@media only screen and (min-width: 620px) {
+  #sidebar-toggle-anchor:checked ~ .page-wrapper {
+    transform: none;
+    margin-inline-start: calc(
+      var(--sidebar-width) + var(--sidebar-resize-indicator-width)
+    );
+  }
+  [dir="rtl"] #sidebar-toggle-anchor:checked ~ .page-wrapper {
+    transform: none;
+  }
+}
+
+.chapter {
+  list-style: none outside none;
+  padding-inline-start: 0;
+  line-height: 2.2em;
+}
+
+.chapter ol {
+  width: 100%;
+}
+
+.chapter li {
+  display: flex;
+  color: var(--sidebar-non-existent);
+}
+.chapter li a {
+  display: block;
+  padding: 0;
+  text-decoration: none;
+  color: var(--sidebar-fg);
+}
+
+.chapter li a:hover {
+  color: var(--sidebar-active);
+}
+
+.chapter li a.active {
+  color: var(--sidebar-active);
+}
+
+.chapter li > a.toggle {
+  cursor: pointer;
+  display: block;
+  margin-inline-start: auto;
+  padding: 0 10px;
+  user-select: none;
+  opacity: 0.68;
+}
+
+.chapter li > a.toggle div {
+  transition: transform 0.5s;
+}
+
+/* collapse the section */
+.chapter li:not(.expanded) + li > ol {
+  display: none;
+}
+
+.chapter li.chapter-item {
+  line-height: 1.5em;
+  margin-block-start: 0.6em;
+}
+
+.chapter li.expanded > a.toggle div {
+  transform: rotate(90deg);
+}
+
+.spacer {
+  width: 100%;
+  height: 3px;
+  margin: 5px 0px;
+}
+.chapter .spacer {
+  background-color: var(--sidebar-spacer);
+}
+
+@media (-moz-touch-enabled: 1), (pointer: coarse) {
+  .chapter li a {
+    padding: 5px 0;
+  }
+  .spacer {
+    margin: 10px 0;
+  }
+}
+
+.section {
+  list-style: none outside none;
+  padding-inline-start: 20px;
+  line-height: 1.9em;
+}
+
+/* Theme Menu Popup */
+
+.theme-popup {
+  position: absolute;
+  left: 10px;
+  top: var(--menu-bar-height);
+  z-index: 1000;
+  border-radius: 4px;
+  font-size: 0.7em;
+  color: var(--fg);
+  background: var(--theme-popup-bg);
+  border: 1px solid var(--theme-popup-border);
+  margin: 0;
+  padding: 0;
+  list-style: none;
+  display: none;
+  /* Don't let the children's background extend past the rounded corners. */
+  overflow: hidden;
+}
+[dir="rtl"] .theme-popup {
+  left: unset;
+  right: 10px;
+}
+.theme-popup .default {
+  color: var(--icons);
+}
+.theme-popup .theme {
+  width: 100%;
+  border: 0;
+  margin: 0;
+  padding: 2px 20px;
+  line-height: 25px;
+  white-space: nowrap;
+  text-align: start;
+  cursor: pointer;
+  color: inherit;
+  background: inherit;
+  font-size: inherit;
+}
+.theme-popup .theme:hover {
+  background-color: var(--theme-hover);
+}
+
+.theme-selected::before {
+  display: inline-block;
+  content: "✓";
+  margin-inline-start: -14px;
+  width: 14px;
+}
diff --git a/theme/css/general.css b/theme/css/general.css
new file mode 100644
index 00000000..8d82f004
--- /dev/null
+++ b/theme/css/general.css
@@ -0,0 +1,279 @@
+/* Base styles and content styles */
+
+:root {
+  /* Browser default font-size is 16px, this way 1 rem = 10px */
+  font-size: 62.5%;
+  color-scheme: var(--color-scheme);
+}
+
+html {
+  font-family: "Open Sans", sans-serif;
+  color: var(--fg);
+  background-color: var(--bg);
+  text-size-adjust: none;
+  -webkit-text-size-adjust: none;
+}
+
+body {
+  margin: 0;
+  font-size: 1.6rem;
+  overflow-x: hidden;
+}
+
+code {
+  font-family: var(--mono-font) !important;
+  font-size: var(--code-font-size);
+  direction: ltr !important;
+}
+
+/* make long words/inline code not x overflow */
+main {
+  overflow-wrap: break-word;
+}
+
+/* make wide tables scroll if they overflow */
+.table-wrapper {
+  overflow-x: auto;
+}
+
+/* Don't change font size in headers. */
+h1 code,
+h2 code,
+h3 code,
+h4 code,
+h5 code,
+h6 code {
+  font-size: unset;
+}
+
+.left {
+  float: left;
+}
+.right {
+  float: right;
+}
+.boring {
+  opacity: 0.6;
+}
+.hide-boring .boring {
+  display: none;
+}
+.hidden {
+  display: none !important;
+}
+
+h2 {
+  margin-block-start: 2.5em;
+}
+h3,
+h4,
+h5 {
+  margin-block-start: 2em;
+}
+
+.header + .header h3,
+.header + .header h4,
+.header + .header h5 {
+  margin-block-start: 1em;
+}
+
+h1:target::before,
+h2:target::before,
+h3:target::before,
+h4:target::before,
+h5:target::before,
+h6:target::before {
+  display: inline-block;
+  content: "»";
+  margin-inline-start: -30px;
+  width: 30px;
+}
+
+/* This is broken on Safari as of version 14, but is fixed
+   in Safari Technology Preview 117 which I think will be Safari 14.2.
+   https://bugs.webkit.org/show_bug.cgi?id=218076
+*/
+:target {
+  /* Safari does not support logical properties */
+  scroll-margin-top: calc(var(--menu-bar-height) + 0.5em);
+}
+
+.page {
+  outline: 0;
+  padding: 0 var(--page-padding);
+  margin-block-start: calc(
+    0px - var(--menu-bar-height)
+  ); /* Compensate for the #menu-bar-hover-placeholder */
+}
+.page-wrapper {
+  box-sizing: border-box;
+  background-color: var(--bg);
+}
+.no-js .page-wrapper,
+.js:not(.sidebar-resizing) .page-wrapper {
+  transition: margin-left 0.3s ease, transform 0.3s ease; /* Animation: slide away */
+}
+[dir="rtl"] .js:not(.sidebar-resizing) .page-wrapper {
+  transition: margin-right 0.3s ease, transform 0.3s ease; /* Animation: slide away */
+}
+
+.content {
+  overflow-y: auto;
+  padding: 0 5px 50px 5px;
+}
+.content main {
+  margin-inline-start: auto;
+  margin-inline-end: auto;
+  max-width: var(--content-max-width);
+}
+.content p {
+  line-height: 1.45em;
+}
+.content ol {
+  line-height: 1.45em;
+}
+.content ul {
+  line-height: 1.45em;
+}
+.content a {
+  text-decoration: underline;
+}
+.content a:hover {
+  text-decoration: underline dotted;
+}
+.content img,
+.content video {
+  max-width: 100%;
+}
+.content .header:link,
+.content .header:visited {
+  color: var(--fg);
+}
+.content .header:link,
+.content .header:visited:hover {
+  text-decoration: none;
+}
+
+table {
+  margin: 0 auto;
+  border-collapse: collapse;
+}
+table td {
+  padding: 3px 20px;
+  border: 1px var(--table-border-color) solid;
+}
+table thead {
+  background: var(--table-header-bg);
+}
+table thead td {
+  font-weight: 700;
+  border: none;
+}
+table thead th {
+  padding: 3px 20px;
+}
+table thead tr {
+  border: 1px var(--table-header-bg) solid;
+}
+/* Alternate background colors for rows */
+table tbody tr:nth-child(2n) {
+  background: var(--table-alternate-bg);
+}
+
+blockquote {
+  margin: 20px 0;
+  padding: 0 20px;
+  color: var(--fg);
+  background-color: var(--quote-bg);
+  border-block-start: 0.1em solid var(--quote-border);
+  border-block-end: 0.1em solid var(--quote-border);
+}
+
+.warning {
+  margin: 20px;
+  padding: 0 20px;
+  border-inline-start: 2px solid var(--warning-border);
+}
+
+.warning:before {
+  position: absolute;
+  width: 3rem;
+  height: 3rem;
+  margin-inline-start: calc(-1.5rem - 21px);
+  content: "ⓘ";
+  text-align: center;
+  background-color: var(--bg);
+  color: var(--warning-border);
+  font-weight: bold;
+  font-size: 2rem;
+}
+
+blockquote .warning:before {
+  background-color: var(--quote-bg);
+}
+
+kbd {
+  background-color: var(--table-border-color);
+  border-radius: 4px;
+  border: solid 1px var(--theme-popup-border);
+  box-shadow: inset 0 -1px 0 var(--theme-hover);
+  display: inline-block;
+  font-size: var(--code-font-size);
+  font-family: var(--mono-font);
+  line-height: 10px;
+  padding: 4px 5px;
+  vertical-align: middle;
+}
+
+sup {
+  /* Set the line-height for superscript and footnote references so that there
+       isn't an awkward space appearing above lines that contain the footnote.
+
+       See https://github.com/rust-lang/mdBook/pull/2443#discussion_r1813773583
+       for an explanation.
+    */
+  line-height: 0;
+}
+
+:not(.footnote-definition) + .footnote-definition,
+.footnote-definition + :not(.footnote-definition) {
+  margin-block-start: 2em;
+}
+.footnote-definition {
+  font-size: 0.9em;
+  margin: 0.5em 0;
+}
+.footnote-definition p {
+  display: inline;
+}
+
+.tooltiptext {
+  position: absolute;
+  visibility: hidden;
+  color: #fff;
+  background-color: #333;
+  transform: translateX(
+    -50%
+  ); /* Center by moving tooltip 50% of its width left */
+  left: -8px; /* Half of the width of the icon */
+  top: -35px;
+  font-size: 0.8em;
+  text-align: center;
+  border-radius: 6px;
+  padding: 5px 8px;
+  margin: 5px;
+  z-index: 1000;
+}
+.tooltipped .tooltiptext {
+  visibility: visible;
+}
+
+.chapter li.part-title {
+  color: var(--sidebar-fg);
+  margin: 5px 0px;
+  font-weight: bold;
+}
+
+.result-no-output {
+  font-style: italic;
+}
diff --git a/theme/css/speaker-notes.css b/theme/css/speaker-notes.css
index 7c14a17f..a16e1bee 100644
--- a/theme/css/speaker-notes.css
+++ b/theme/css/speaker-notes.css
@@ -5,16 +5,17 @@
   padding: 0.25em;
 }
 
-.content details summary h4 {
+.content details summary h3 {
   display: inline-block;
   list-style: none;
   font-weight: normal;
   font-style: italic;
+  font-size: 1.6rem;
   margin: 0.5em 0.25em;
   cursor: pointer;
 }
 
-.content details summary h4:target::before {
+.content details summary h3:target::before {
   margin-left: -40px;
   width: 40px;
 }
diff --git a/theme/index.hbs b/theme/index.hbs
index 625d6443..8be38847 100644
--- a/theme/index.hbs
+++ b/theme/index.hbs
@@ -289,7 +289,6 @@
 
                 <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
                 <script>
-                    document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
                     document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
                     Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
                         link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
diff --git a/theme/speaker-notes.js b/theme/speaker-notes.js
index 6247ea3f..537f6214 100644
--- a/theme/speaker-notes.js
+++ b/theme/speaker-notes.js
@@ -95,21 +95,23 @@
     let summary = document.createElement("summary");
     notes.insertBefore(summary, notes.firstChild);
 
-    let h4 = document.createElement("h4");
-    h4.setAttribute("id", "speaker-notes");
-    h4.append("Speaker Notes");
-    h4.addEventListener("click", (event) => {
+    let h3 = document.createElement("h3");
+    h3.setAttribute("id", "speaker-notes");
+    h3.append("Speaker Notes");
+    h3.addEventListener("click", (event) => {
       // Update fragment as if we had clicked a link. A regular a element would
       // result in double-fire of the event.
       window.location.hash = "#speaker-notes";
     });
-    summary.append(h4);
+    summary.append(h3);
 
     // Create pop-out button.
     let popOutLocation = new URL(window.location.href);
     popOutLocation.hash = "#speaker-notes-open";
     let popOut = document.createElement("button");
     popOut.classList.add("icon-button", "pop-out");
+    popOut.setAttribute("title", "Open speaker notes in a new window");
+    popOut.setAttribute("aria-label", "Open speaker notes in a new window");
     popOut.addEventListener("click", (event) => {
       let popup = window.open(popOutLocation.href, "speakerNotes", "popup");
       if (popup) {