diff --git a/mobile/android/themes/core/aboutReader.css b/mobile/android/themes/core/aboutReader.css
index 2df2d1ff6206..32f52080c04d 100644
--- a/mobile/android/themes/core/aboutReader.css
+++ b/mobile/android/themes/core/aboutReader.css
@@ -118,3 +118,409 @@ body.dark > .container > .content blockquote {
   color: #aaaaaa !important;
   border-left-color: #777777 !important;
 }
+
+#reader-message {
+  margin-top: 40px;
+  display: none;
+  text-align: center;
+  width: 100%;
+  font-size: 0.9em;
+}
+
+.header {
+  text-align: start;
+  display: none;
+}
+
+.domain,
+.credits {
+  font-size: 0.9em;
+  font-family: sans-serif;
+}
+
+.domain {
+  margin-top: 10px;
+  padding-bottom: 10px;
+  color: #00acff !important;
+  text-decoration: none;
+}
+
+.domain-border {
+  margin-top: 15px;
+  border-bottom: 1.5px solid #777777;
+  width: 50%;
+}
+
+.header > h1 {
+  font-size: 1.33em;
+  font-weight: 700;
+  line-height: 1.1em;
+  width: 100%;
+  margin: 0px;
+  margin-top: 32px;
+  margin-bottom: 16px;
+  padding: 0px;
+}
+
+.header > .credits {
+  padding: 0px;
+  margin: 0px;
+  margin-bottom: 32px;
+}
+
+/*======= Controls toolbar =======*/
+
+.toolbar {
+  font-family: sans-serif;
+  position: fixed;
+  width: 100%;
+  left: 0;
+  margin: 0;
+  padding: 0;
+  bottom: 0;
+  list-style: none;
+  pointer-events: none;
+  transition: opacity 420ms linear;
+}
+
+.toolbar > * {
+  float: right;
+}
+
+.button {
+  width: 56px;
+  height: 56px;
+  display: block;
+  background-position: center;
+  background-size: 26px 16px;
+  background-repeat: no-repeat;
+  background-color: #0979D9;
+  border-radius: 10000px;
+  margin: 20px;
+  border: 0;
+  box-shadow: 0px 4px 8px 0px rgba(0,0,0,0.40);
+}
+
+.button:active {
+  background-color: #086ACC;
+}
+
+/* Remove dotted border when button is focused */
+.button::-moz-focus-inner,
+.dropdown-popup > div > button::-moz-focus-inner {
+  border: 0;
+}
+
+.button[hidden],
+.toolbar[hidden] {
+  display: none;
+}
+
+.dropdown-toggle,
+#reader-popup {
+  pointer-events: auto;
+}
+
+.dropdown {
+  left: 0;
+  text-align: center;
+  display: inline-block;
+  list-style: none;
+  margin: 0px;
+  padding: 0px;
+}
+
+/*======= Font style popup =======*/
+
+.dropdown-popup {
+  position: absolute;
+  left: 0;
+  width: calc(100% - 30px);
+  margin: 15px;
+  z-index: 1000;
+  background: #EBEBF0;
+  visibility: hidden;
+  border: 0;
+  border-radius: 4px;
+  box-shadow: 0px 4px 8px 0px rgba(0,0,0,0.40);
+  -moz-user-select: none;
+}
+
+/* Only used on desktop */
+.dropdown-popup > hr,
+.dropdown-arrow,
+#font-type-buttons > button > .name,
+#content-width-buttons,
+#line-height-buttons {
+  display: none;
+}
+
+.open > .dropdown-popup {
+  visibility: visible;
+  bottom: 0;
+}
+
+#font-type-buttons,
+#font-size-buttons,
+#color-scheme-buttons {
+  display: flex;
+  flex-direction: row;
+}
+
+#font-type-buttons > button,
+#color-scheme-buttons > button {
+  text-align: center;
+}
+
+#font-type-buttons > button,
+#font-size-buttons > button {
+  width: 50%;
+  background-color: transparent;
+  border: 0;
+}
+
+#font-type-buttons > button {
+  font-size: 24px;
+  color: #AFB1B3;
+  padding: 15px 0;
+}
+
+#font-type-buttons > button:active,
+#font-type-buttons > button.selected {
+  color: #222222;
+}
+
+#font-size-sample {
+  flex: 0;
+  font-size: 24px;
+  color: #000000;
+  margin: 0 30px;
+  padding: 0 10px;
+}
+
+.serif-button {
+  font-family: serif;
+}
+
+.minus-button,
+.plus-button {
+  background-color: transparent;
+  border: 0;
+  height: 60px;
+  background-size: 18px 18px;
+  background-repeat: no-repeat;
+  background-position: center;
+}
+
+.minus-button {
+  background-size: 24px 6px;
+  margin-left: 50px;
+  padding: 0 5px;
+}
+
+.plus-button {
+  background-size: 24px 24px;
+  margin-right: 50px;
+  padding: 0 5px;
+}
+
+#color-scheme-buttons > button {
+  width: 33%;
+  border-radius: 4px;
+  border: 1px solid #BFBFBF;
+  padding: 10px;
+  margin: 15px 10px;
+  font-size: 14px;
+}
+
+#color-scheme-buttons > button:active,
+#color-scheme-buttons > button.selected {
+  border: 2px solid #0A84FF;
+}
+
+.dark-button {
+  color: #eeeeee;
+  background-color: #333333;
+}
+
+.auto-button {
+  color: #000000;
+  background-color: transparent;
+}
+
+.light-button {
+  color: #333333;
+  background-color: #ffffff;
+}
+
+/*======= Toolbar icons =======*/
+
+/* desktop-only controls */
+.close-button {
+  display: none;
+}
+
+.style-button {
+  background-image: url('chrome://browser/skin/images/reader-style-icon-hdpi.png');
+}
+
+.minus-button {
+  background-image: url('chrome://browser/skin/images/reader-minus-hdpi.png');
+}
+
+.plus-button {
+  background-image: url('chrome://browser/skin/images/reader-plus-hdpi.png');
+}
+
+@media screen and (min-resolution: 2dppx) {
+  .style-button {
+    background-image: url('chrome://browser/skin/images/reader-style-icon-xhdpi.png');
+  }
+
+  .minus-button {
+    background-image: url('chrome://browser/skin/images/reader-minus-xhdpi.png');
+  }
+
+  .plus-button {
+    background-image: url('chrome://browser/skin/images/reader-plus-xhdpi.png');
+  }
+}
+
+@media screen and (min-resolution: 3dppx) {
+  .style-button {
+    background-image: url('chrome://browser/skin/images/reader-style-icon-xxhdpi.png');
+  }
+
+  .minus-button {
+    background-image: url('chrome://browser/skin/images/reader-minus-xxhdpi.png');
+  }
+
+  .plus-button {
+    background-image: url('chrome://browser/skin/images/reader-plus-xxhdpi.png');
+  }
+}
+
+@media screen and (min-width: 960px) {
+  .dropdown-popup {
+    width: 350px;
+    left: auto;
+    right: 0;
+  }
+}
+
+/*======= Article content =======*/
+
+/* Note that any class names from the original article that we want to match on
+ * must be added to CLASSES_TO_PRESERVE in ReaderMode.jsm, so that
+ * Readability.js doesn't strip them out */
+
+#moz-reader-content {
+  display: none;
+  font-size: 1em;
+}
+
+#moz-reader-content a {
+  text-decoration: underline !important;
+  font-weight: normal;
+}
+
+#moz-reader-content a,
+#moz-reader-content a:visited,
+#moz-reader-content a:hover,
+#moz-reader-content a:active {
+  color: #00acff !important;
+}
+
+#moz-reader-content * {
+  max-width: 100% !important;
+  height: auto !important;
+}
+
+#moz-reader-content p {
+  line-height: 1.4em !important;
+  margin: 0px !important;
+  margin-bottom: 20px !important;
+}
+
+/* Covers all images showing edge-to-edge using a 
+   an optional caption text */
+#moz-reader-content .wp-caption,
+#moz-reader-content figure {
+  display: block !important;
+  width: 100% !important;
+  margin: 0px !important;
+  margin-bottom: 32px !important;
+}
+
+/* Images marked to be shown edge-to-edge with an
+   optional captio ntext */
+#moz-reader-content p > img:only-child,
+#moz-reader-content p > a:only-child > img:only-child,
+#moz-reader-content .wp-caption img,
+#moz-reader-content figure img {
+  display: block;
+  margin-left: auto;
+  margin-right: auto;
+}
+
+/* Account for body padding to make image full width */
+#moz-reader-content img[moz-reader-full-width] {
+  width: calc(100% + 40px);
+  margin-left: -20px;
+  margin-right: -20px;
+  max-width: none !important;
+}
+
+/* Image caption text */
+#moz-reader-content .caption,
+#moz-reader-content .wp-caption-text,
+#moz-reader-content figcaption {
+  font-size: 0.9em;
+  font-family: sans-serif;
+  margin: 0px !important;
+  padding-top: 4px !important;
+}
+
+/* Ensure all pre-formatted code inside the reader content
+   are properly wrapped inside content width */
+#moz-reader-content code,
+#moz-reader-content pre {
+  white-space: pre-wrap !important;
+  margin-bottom: 20px !important;
+}
+
+#moz-reader-content blockquote {
+  margin: 0px !important;
+  margin-bottom: 20px !important;
+  padding: 0px !important;
+  padding-inline-start: 16px !important;
+  border: 0px !important;
+  border-left: 2px solid !important;
+}
+
+#moz-reader-content ul,
+#moz-reader-content ol {
+  margin: 0px !important;
+  margin-bottom: 20px !important;
+  padding: 0px !important;
+  line-height: 1.5em;
+}
+
+#moz-reader-content ul {
+  padding-inline-start: 30px !important;
+  list-style: disc !important;
+}
+
+#moz-reader-content ol {
+  padding-inline-start: 35px !important;
+  list-style: decimal !important;
+}
+
+/* Hide elements with common "hidden" class names */
+#moz-reader-content .visually-hidden,
+#moz-reader-content .visuallyhidden,
+#moz-reader-content .hidden,
+#moz-reader-content .invisible,
+#moz-reader-content .sr-only {
+  display: none;
+}
diff --git a/mobile/android/themes/core/aboutReaderContent.css b/mobile/android/themes/core/aboutReaderContent.css
deleted file mode 100644
index fe6451df2f52..000000000000
--- a/mobile/android/themes/core/aboutReaderContent.css
+++ /dev/null
@@ -1,114 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#moz-reader-content {
-  display: none;
-  font-size: 1em;
-}
-
-a {
-  text-decoration: underline !important;
-  font-weight: normal;
-}
-
-a,
-a:visited,
-a:hover,
-a:active {
-  color: #00acff !important;
-}
-
-* {
-  max-width: 100% !important;
-  height: auto !important;
-}
-
-p {
-  line-height: 1.4em !important;
-  margin: 0px !important;
-  margin-bottom: 20px !important;
-}
-
-/* Covers all images showing edge-to-edge using a 
-   an optional caption text */
-.wp-caption,
-figure {
-  display: block !important;
-  width: 100% !important;
-  margin: 0px !important;
-  margin-bottom: 32px !important;
-}
-
-/* Images marked to be shown edge-to-edge with an
-   optional captio ntext */
-p > img:only-child,
-p > a:only-child > img:only-child,
-.wp-caption img,
-figure img {
-  display: block;
-  margin-left: auto;
-  margin-right: auto;
-}
-
-/* Account for body padding to make image full width */
-img[moz-reader-full-width] {
-  width: calc(100% + 40px);
-  margin-left: -20px;
-  margin-right: -20px;
-  max-width: none !important;
-}
-
-/* Image caption text */
-.caption,
-.wp-caption-text,
-figcaption {
-  font-size: 0.9em;
-  font-family: sans-serif;
-  margin: 0px !important;
-  padding-top: 4px !important;
-}
-
-/* Ensure all pre-formatted code inside the reader content
-   are properly wrapped inside content width */
-code,
-pre {
-  white-space: pre-wrap !important;
-  margin-bottom: 20px !important;
-}
-
-blockquote {
-  margin: 0px !important;
-  margin-bottom: 20px !important;
-  padding: 0px !important;
-  padding-inline-start: 16px !important;
-  border: 0px !important;
-  border-left: 2px solid !important;
-}
-
-ul,
-ol {
-  margin: 0px !important;
-  margin-bottom: 20px !important;
-  padding: 0px !important;
-  line-height: 1.5em;
-}
-
-ul {
-  padding-inline-start: 30px !important;
-  list-style: disc !important;
-}
-
-ol {
-  padding-inline-start: 35px !important;
-  list-style: decimal !important;
-}
-
-/* Hide elements with common "hidden" class names */
-.visually-hidden,
-.visuallyhidden,
-.hidden,
-.invisible,
-.sr-only {
-  display: none;
-}
diff --git a/mobile/android/themes/core/aboutReaderControls.css b/mobile/android/themes/core/aboutReaderControls.css
deleted file mode 100644
index 4bfae9cb0da6..000000000000
--- a/mobile/android/themes/core/aboutReaderControls.css
+++ /dev/null
@@ -1,292 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#reader-message {
-  margin-top: 40px;
-  display: none;
-  text-align: center;
-  width: 100%;
-  font-size: 0.9em;
-}
-
-.header {
-  text-align: start;
-  display: none;
-}
-
-.domain,
-.credits {
-  font-size: 0.9em;
-  font-family: sans-serif;
-}
-
-.domain {
-  margin-top: 10px;
-  padding-bottom: 10px;
-  color: #00acff !important;
-  text-decoration: none;
-}
-
-.domain-border {
-  margin-top: 15px;
-  border-bottom: 1.5px solid #777777;
-  width: 50%;
-}
-
-.header > h1 {
-  font-size: 1.33em;
-  font-weight: 700;
-  line-height: 1.1em;
-  width: 100%;
-  margin: 0px;
-  margin-top: 32px;
-  margin-bottom: 16px;
-  padding: 0px;
-}
-
-.header > .credits {
-  padding: 0px;
-  margin: 0px;
-  margin-bottom: 32px;
-}
-
-/*======= Controls toolbar =======*/
-
-.toolbar {
-  font-family: sans-serif;
-  position: fixed;
-  width: 100%;
-  left: 0;
-  margin: 0;
-  padding: 0;
-  bottom: 0;
-  list-style: none;
-  pointer-events: none;
-  transition: opacity 420ms linear;
-}
-
-.toolbar > * {
-  float: right;
-}
-
-.button {
-  width: 56px;
-  height: 56px;
-  display: block;
-  background-position: center;
-  background-size: 26px 16px;
-  background-repeat: no-repeat;
-  background-color: #0979D9;
-  border-radius: 10000px;
-  margin: 20px;
-  border: 0;
-  box-shadow: 0px 4px 8px 0px rgba(0,0,0,0.40);
-}
-
-.button:active {
-  background-color: #086ACC;
-}
-
-/* Remove dotted border when button is focused */
-.button::-moz-focus-inner,
-.dropdown-popup > div > button::-moz-focus-inner {
-  border: 0;
-}
-
-.button[hidden],
-.toolbar[hidden] {
-  display: none;
-}
-
-.dropdown-toggle,
-#reader-popup {
-  pointer-events: auto;
-}
-
-.dropdown {
-  left: 0;
-  text-align: center;
-  display: inline-block;
-  list-style: none;
-  margin: 0px;
-  padding: 0px;
-}
-
-/*======= Font style popup =======*/
-
-.dropdown-popup {
-  position: absolute;
-  left: 0;
-  width: calc(100% - 30px);
-  margin: 15px;
-  z-index: 1000;
-  background: #EBEBF0;
-  visibility: hidden;
-  border: 0;
-  border-radius: 4px;
-  box-shadow: 0px 4px 8px 0px rgba(0,0,0,0.40);
-  -moz-user-select: none;
-}
-
-/* Only used on desktop */
-.dropdown-popup > hr,
-.dropdown-arrow,
-#font-type-buttons > button > .name,
-#content-width-buttons,
-#line-height-buttons {
-  display: none;
-}
-
-.open > .dropdown-popup {
-  visibility: visible;
-  bottom: 0;
-}
-
-#font-type-buttons,
-#font-size-buttons,
-#color-scheme-buttons {
-  display: flex;
-  flex-direction: row;
-}
-
-#font-type-buttons > button,
-#color-scheme-buttons > button {
-  text-align: center;
-}
-
-#font-type-buttons > button,
-#font-size-buttons > button {
-  width: 50%;
-  background-color: transparent;
-  border: 0;
-}
-
-#font-type-buttons > button {
-  font-size: 24px;
-  color: #AFB1B3;
-  padding: 15px 0;
-}
-
-#font-type-buttons > button:active,
-#font-type-buttons > button.selected {
-  color: #222222;
-}
-
-#font-size-sample {
-  flex: 0;
-  font-size: 24px;
-  color: #000000;
-  margin: 0 30px;
-  padding: 0 10px;
-}
-
-.serif-button {
-  font-family: serif;
-}
-
-.minus-button,
-.plus-button {
-  background-color: transparent;
-  border: 0;
-  height: 60px;
-  background-size: 18px 18px;
-  background-repeat: no-repeat;
-  background-position: center;
-}
-
-.minus-button {
-  background-size: 24px 6px;
-  margin-left: 50px;
-  padding: 0 5px;
-}
-
-.plus-button {
-  background-size: 24px 24px;
-  margin-right: 50px;
-  padding: 0 5px;
-}
-
-#color-scheme-buttons > button {
-  width: 33%;
-  border-radius: 4px;
-  border: 1px solid #BFBFBF;
-  padding: 10px;
-  margin: 15px 10px;
-  font-size: 14px;
-}
-
-#color-scheme-buttons > button:active,
-#color-scheme-buttons > button.selected {
-  border: 2px solid #0A84FF;
-}
-
-.dark-button {
-  color: #eeeeee;
-  background-color: #333333;
-}
-
-.auto-button {
-  color: #000000;
-  background-color: transparent;
-}
-
-.light-button {
-  color: #333333;
-  background-color: #ffffff;
-}
-
-/*======= Toolbar icons =======*/
-
-/* desktop-only controls */
-.close-button {
-  display: none;
-}
-
-.style-button {
-  background-image: url('chrome://browser/skin/images/reader-style-icon-hdpi.png');
-}
-
-.minus-button {
-  background-image: url('chrome://browser/skin/images/reader-minus-hdpi.png');
-}
-
-.plus-button {
-  background-image: url('chrome://browser/skin/images/reader-plus-hdpi.png');
-}
-
-@media screen and (min-resolution: 2dppx) {
-  .style-button {
-    background-image: url('chrome://browser/skin/images/reader-style-icon-xhdpi.png');
-  }
-
-  .minus-button {
-    background-image: url('chrome://browser/skin/images/reader-minus-xhdpi.png');
-  }
-
-  .plus-button {
-    background-image: url('chrome://browser/skin/images/reader-plus-xhdpi.png');
-  }
-}
-
-@media screen and (min-resolution: 3dppx) {
-  .style-button {
-    background-image: url('chrome://browser/skin/images/reader-style-icon-xxhdpi.png');
-  }
-
-  .minus-button {
-    background-image: url('chrome://browser/skin/images/reader-minus-xxhdpi.png');
-  }
-
-  .plus-button {
-    background-image: url('chrome://browser/skin/images/reader-plus-xxhdpi.png');
-  }
-}
-
-@media screen and (min-width: 960px) {
-  .dropdown-popup {
-    width: 350px;
-    left: auto;
-    right: 0;
-  }
-}
diff --git a/mobile/android/themes/core/jar.mn b/mobile/android/themes/core/jar.mn
index 560bb6f319db..c07c0de67b55 100644
--- a/mobile/android/themes/core/jar.mn
+++ b/mobile/android/themes/core/jar.mn
@@ -15,8 +15,6 @@ chrome.jar:
   skin/aboutMemory.css                      (aboutMemory.css)
   skin/aboutPrivateBrowsing.css             (aboutPrivateBrowsing.css)
   skin/aboutReader.css                      (aboutReader.css)
-  skin/aboutReaderContent.css               (aboutReaderContent.css)
-  skin/aboutReaderControls.css              (aboutReaderControls.css)
   skin/aboutSupport.css                     (aboutSupport.css)
   skin/config.css                           (config.css)
   skin/defines.css                          (defines.css)
@@ -25,8 +23,6 @@ chrome.jar:
 % override chrome://global/skin/about.css chrome://browser/skin/about.css
 % override chrome://global/skin/aboutMemory.css chrome://browser/skin/aboutMemory.css
 % override chrome://global/skin/aboutReader.css chrome://browser/skin/aboutReader.css
-% override chrome://global/skin/aboutReaderContent.css chrome://browser/skin/aboutReaderContent.css
-% override chrome://global/skin/aboutReaderControls.css chrome://browser/skin/aboutReaderControls.css
 % override chrome://global/skin/aboutSupport.css chrome://browser/skin/aboutSupport.css
 % override chrome://global/skin/netError.css chrome://browser/skin/netError.css
 
diff --git a/toolkit/components/narrate/NarrateControls.jsm b/toolkit/components/narrate/NarrateControls.jsm
index 35c2b0bccf99..c202ff627d57 100644
--- a/toolkit/components/narrate/NarrateControls.jsm
+++ b/toolkit/components/narrate/NarrateControls.jsm
@@ -41,13 +41,9 @@ function NarrateControls(mm, win, languagePromise) {
   dropdown.className = "dropdown";
   dropdown.id = "narrate-dropdown";
   // We need inline svg here for the animation to work (bug 908634 & 1190881).
-  // The style animation can't be scoped (bug 830056).
   // eslint-disable-next-line no-unsanitized/property
   dropdown.innerHTML =
-    localize`<style scoped>
-      @import url("chrome://global/skin/narrateControls.css");
-    </style>
-    <li>
+    localize`<li>
        <button class="dropdown-toggle button" id="narrate-toggle"
                title="${"narrate"}" hidden>
          <svg xmlns="http://www.w3.org/2000/svg"
diff --git a/toolkit/components/printing/content/simplifyMode.css b/toolkit/components/printing/content/simplifyMode.css
index 4ad692228304..257acad91b45 100644
--- a/toolkit/components/printing/content/simplifyMode.css
+++ b/toolkit/components/printing/content/simplifyMode.css
@@ -4,9 +4,9 @@
 
 /* This file defines specific rules for print preview when using simplify mode.
  * Some of these rules (styling for title and author on the header element)
- * already exist on aboutReaderControls.css, however, we decoupled it from the
- * original file so we don't need to load a bunch of extra queries that will not
- * take effect when using the simplify page checkbox. */
+ * already exist in aboutReader.css, however, we decoupled it from the original
+ * file so we don't need to load a bunch of extra queries that will not take
+ * effect when using the simplify page checkbox. */
 
 body {
   padding-top: 0px;
@@ -29,4 +29,4 @@ body {
   line-height: 1.48em;
   margin: 0 0 30px 0;
   font-style: italic;
-}
\ No newline at end of file
+}
diff --git a/toolkit/components/reader/content/aboutReader.html b/toolkit/components/reader/content/aboutReader.html
index 53d5a2b47567..635ba6bdb5b5 100644
--- a/toolkit/components/reader/content/aboutReader.html
+++ b/toolkit/components/reader/content/aboutReader.html
@@ -13,9 +13,6 @@
 <body>
   <div id="container" class="container">
     <div id="reader-header" class="header">
-      <style scoped>
-        @import url("chrome://global/skin/aboutReaderControls.css");
-      </style>
       <a id="reader-domain" class="domain"></a>
       <div class="domain-border"></div>
       <h1 id="reader-title"></h1>
@@ -28,24 +25,15 @@
     <hr>
 
     <div class="content">
-      <style scoped>
-        @import url("chrome://global/skin/aboutReaderContent.css");
-      </style>
       <div id="moz-reader-content"></div>
     </div>
 
     <div>
-      <style scoped>
-        @import url("chrome://global/skin/aboutReaderControls.css");
-      </style>
       <div id="reader-message"></div>
     </div>
   </div>
 
   <ul id="reader-toolbar" class="toolbar">
-    <style scoped>
-      @import url("chrome://global/skin/aboutReaderControls.css");
-    </style>
     <li><button id="close-button" class="button close-button"/></li>
     <ul id="style-dropdown" class="dropdown">
       <li><button class="dropdown-toggle button style-button"/></li>
diff --git a/toolkit/content/browser-content.js b/toolkit/content/browser-content.js
index c686f86476a5..63116f09cc2e 100644
--- a/toolkit/content/browser-content.js
+++ b/toolkit/content/browser-content.js
@@ -677,12 +677,6 @@ var Printing = {
       contentElement.setAttribute("class", "content");
       containerElement.appendChild(contentElement);
 
-      // Create style element for content div and import aboutReaderContent.css
-      let controlContentStyle = content.document.createElement("style");
-      controlContentStyle.setAttribute("scoped", "");
-      controlContentStyle.textContent = "@import url(\"chrome://global/skin/aboutReaderContent.css\");";
-      contentElement.appendChild(controlContentStyle);
-
       // Jam the article's content into content div
       let readerContent = content.document.createElement("div");
       readerContent.setAttribute("id", "moz-reader-content");
diff --git a/toolkit/themes/shared/aboutReader.css b/toolkit/themes/shared/aboutReader.css
index 36945def6ca9..7b63f56e3e84 100644
--- a/toolkit/themes/shared/aboutReader.css
+++ b/toolkit/themes/shared/aboutReader.css
@@ -163,3 +163,576 @@ body:not(.loaded) .toolbar:-moz-locale-dir(ltr) {
 body:not(.loaded) .toolbar:-moz-locale-dir(rtl) {
   transform: translateX(100%);
 }
+
+.light-button {
+  color: #333333;
+  background-color: #ffffff;
+}
+
+.dark-button {
+  color: #eeeeee;
+  background-color: #333333;
+}
+
+.sepia-button {
+  color: #5b4636;
+  background-color: #f4ecd8;
+}
+
+.sans-serif-button {
+  font-family: Helvetica, Arial, sans-serif;
+}
+
+.serif-button {
+  font-family: Georgia, "Times New Roman", serif;
+}
+
+/* Loading/error message */
+
+#reader-message {
+  margin-top: 40px;
+  display: none;
+  text-align: center;
+  width: 100%;
+  font-size: 0.9em;
+}
+
+/* Header */
+
+.header {
+  text-align: start;
+  display: none;
+}
+
+.domain {
+  font-size: 0.9em;
+  line-height: 1.48em;
+  padding-bottom: 4px;
+  font-family: Helvetica, Arial, sans-serif;
+  text-decoration: none;
+  border-bottom: 1px solid;
+  color: #0095dd;
+}
+
+.header > h1 {
+  font-size: 1.6em;
+  line-height: 1.25em;
+  width: 100%;
+  margin: 30px 0;
+  padding: 0;
+}
+
+.header > .credits {
+  font-size: 0.9em;
+  line-height: 1.48em;
+  margin: 0 0 10px 0;
+  padding: 0;
+  font-style: italic;
+}
+
+.header > .meta-data {
+  font-size: 0.65em;
+  margin: 0 0 15px 0;
+}
+
+/*======= Controls toolbar =======*/
+
+.toolbar {
+  font-family: Helvetica, Arial, sans-serif;
+  position: fixed;
+  height: 100%;
+  top: 0;
+  left: 0;
+  margin: 0;
+  padding: 0;
+  list-style: none;
+  background-color: #fbfbfb;
+  -moz-user-select: none;
+  border-right: 1px solid #b5b5b5;
+  z-index: 1;
+}
+
+.button {
+  display: block;
+  background-size: 24px 24px;
+  background-repeat: no-repeat;
+  color: #333;
+  background-color: #fbfbfb;
+  height: 40px;
+  padding: 0;
+}
+
+.toolbar .button {
+  width: 40px;
+  background-position: center;
+  margin-right: -1px;
+  border-top: 0;
+  border-left: 0;
+  border-right: 1px solid #b5b5b5;
+  border-bottom: 1px solid #c1c1c1;
+}
+
+.button[hidden] {
+  display: none;
+}
+
+.dropdown {
+  text-align: center;
+  list-style: none;
+  margin: 0;
+  padding: 0;
+}
+
+.dropdown li {
+  margin: 0;
+  padding: 0;
+}
+
+/*======= Popup =======*/
+
+.dropdown-popup {
+  min-width: 300px;
+  text-align: start;
+  position: absolute;
+  left: 48px; /* offset to account for toolbar width */
+  z-index: 1000;
+  background-color: #fbfbfb;
+  visibility: hidden;
+  border-radius: 4px;
+  border: 1px solid #b5b5b5;
+  border-bottom-width: 0;
+  box-shadow: 0 1px 3px #c1c1c1;
+}
+
+.keep-open .dropdown-popup {
+  z-index: initial;
+}
+
+.dropdown-popup > hr {
+  display: none;
+}
+
+.open > .dropdown-popup {
+  visibility: visible;
+}
+
+.dropdown-arrow {
+  position: absolute;
+  top: 30px; /* offset arrow from top of popup */
+  left: -16px;
+  width: 16px;
+  height: 24px;
+  background-image: url("chrome://global/skin/reader/RM-Type-Controls-Arrow.svg");
+  display: block;
+}
+
+/*======= Font style popup =======*/
+
+#font-type-buttons,
+#font-size-buttons,
+#color-scheme-buttons,
+#content-width-buttons,
+#line-height-buttons {
+  display: flex;
+  flex-direction: row;
+}
+
+#font-type-buttons > button:first-child {
+  border-top-left-radius: 3px;
+}
+#font-type-buttons > button:last-child {
+  border-top-right-radius: 3px;
+}
+#color-scheme-buttons > button:first-child {
+  border-bottom-left-radius: 3px;
+}
+#color-scheme-buttons > button:last-child {
+  border-bottom-right-radius: 3px;
+}
+
+#font-type-buttons > button,
+#font-size-buttons > button,
+#color-scheme-buttons > button,
+#content-width-buttons > button,
+#line-height-buttons > button {
+  text-align: center;
+  border: 0;
+}
+
+#font-type-buttons > button,
+#font-size-buttons > button,
+#content-width-buttons > button,
+#line-height-buttons > button {
+  width: 50%;
+  background-color: transparent;
+  border-left: 1px solid #B5B5B5;
+  border-bottom: 1px solid #B5B5B5;
+}
+
+#color-scheme-buttons > button {
+  width: 33.33%;
+  font-size: 14px;
+}
+
+#color-scheme-buttons > .dark-button {
+  margin-top: -1px;
+  height: 61px;
+}
+
+#font-type-buttons > button:first-child,
+#font-size-buttons > button:first-child,
+#content-width-buttons > button:first-child,
+#line-height-buttons > button:first-child {
+  border-left: 0;
+}
+
+#font-type-buttons > button {
+  display: inline-block;
+  font-size: 62px;
+  height: 100px;
+}
+
+#font-size-buttons > button,
+#color-scheme-buttons > button,
+#content-width-buttons > button,
+#line-height-buttons > button {
+  height: 60px;
+}
+
+#font-type-buttons > button:active:hover,
+#font-type-buttons > button.selected,
+#color-scheme-buttons > button:active:hover,
+#color-scheme-buttons > button.selected {
+  box-shadow: inset 0 -3px 0 0 #fc6420;
+}
+
+#font-type-buttons > button:active:hover,
+#font-type-buttons > button.selected {
+  border-bottom: 1px solid #FC6420;
+}
+
+/* Make the serif button content the same size as the sans-serif button content. */
+#font-type-buttons > button > .description {
+  color: #666;
+  font-size: 12px;
+  margin-top: -5px;
+}
+
+/* Font sizes are different per-platform, so we need custom CSS to line them up. */
+%ifdef XP_MACOSX
+#font-type-buttons > .sans-serif-button > .name {
+  margin-top: 10px;
+}
+
+#font-type-buttons > .sans-serif-button > .description {
+  margin-top: -4px;
+}
+
+#font-type-buttons > .serif-button > .name {
+  font-size: 63px;
+}
+%elifdef XP_WIN
+#font-type-buttons > .sans-serif-button > .name {
+  margin-top: 2px;
+}
+
+#font-type-buttons > .sans-serif-button > .description {
+  margin-top: -4px;
+}
+
+#font-type-buttons > .serif-button > .name {
+  font-size: 63px;
+}
+%else
+#font-type-buttons > .sans-serif-button > .name {
+  margin-top: 5px;
+}
+
+#font-type-buttons > .sans-serif-button > .description {
+  margin-top: -8px;
+}
+
+#font-type-buttons > .serif-button > .name {
+  font-size: 70px;
+}
+%endif
+
+.button:hover,
+#font-size-buttons > button:hover,
+#font-type-buttons > button:hover,
+#content-width-buttons > button:hover,
+#line-height-buttons > button:hover {
+  background-color: #ebebeb;
+}
+
+.dropdown.open,
+.button:active,
+#font-size-buttons > button:active,
+#font-size-buttons > button.selected,
+#content-width-buttons > button:active,
+#content-width-buttons > button.selected,
+#line-height-buttons > button:active,
+#line-height-buttons > button.selected {
+  background-color: #dadada;
+}
+
+/* Only used on Android */
+#font-size-sample {
+  display: none;
+}
+
+.minus-button,
+.plus-button,
+.content-width-minus-button,
+.content-width-plus-button,
+.line-height-minus-button,
+.line-height-plus-button {
+  background-color: transparent;
+  border: 0;
+  background-size: 18px 18px;
+  background-repeat: no-repeat;
+  background-position: center;
+}
+
+/*======= Toolbar icons =======*/
+
+.close-button {
+  background-image: url("chrome://global/skin/reader/RM-Close-24x24.svg");
+  -moz-context-properties: fill;
+  fill: #808080;
+  height: 68px;
+  background-position: center 8px;
+}
+
+.close-button:hover {
+  fill: #fff;
+  background-color: #d94141;
+  border-bottom: 1px solid #d94141;
+  border-right: 1px solid #d94141;
+}
+
+.close-button:hover:active {
+  background-color: #AE2325;
+  border-bottom: 1px solid #AE2325;
+  border-right: 1px solid #AE2325;
+}
+
+.style-button {
+  background-image: url("chrome://global/skin/reader/RM-Type-Controls-24x24.svg");
+}
+
+.minus-button {
+  background-image: url("chrome://global/skin/reader/RM-Minus-24x24.svg");
+}
+
+.plus-button {
+  background-image: url("chrome://global/skin/reader/RM-Plus-24x24.svg");
+}
+
+.content-width-minus-button {
+  background-size: 42px 16px;
+  background-image: url("chrome://global/skin/reader/RM-Content-Width-Minus-42x16.svg");
+}
+
+.content-width-plus-button {
+  background-size: 44px 16px;
+  background-image: url("chrome://global/skin/reader/RM-Content-Width-Plus-44x16.svg");
+}
+
+.line-height-minus-button {
+  background-size: 34px 14px;
+  background-image: url("chrome://global/skin/reader/RM-Line-Height-Minus-38x14.svg");
+}
+
+.line-height-plus-button {
+  background-size: 34px 24px;
+  background-image: url("chrome://global/skin/reader/RM-Line-Height-Plus-38x24.svg");
+}
+
+@media print {
+  .toolbar {
+    display: none !important;
+  }
+}
+
+/*======= Article content =======*/
+
+/* Note that any class names from the original article that we want to match on
+ * must be added to CLASSES_TO_PRESERVE in ReaderMode.jsm, so that
+ * Readability.js doesn't strip them out */
+
+#moz-reader-content {
+  display: none;
+  font-size: 1em;
+  line-height: 1.6em;
+}
+
+#moz-reader-content.line-height1 {
+  line-height: 1em;
+}
+
+#moz-reader-content.line-height2 {
+  line-height: 1.2em;
+}
+
+#moz-reader-content.line-height3 {
+  line-height: 1.4em;
+}
+
+#moz-reader-content.line-height4 {
+  line-height: 1.6em;
+}
+
+#moz-reader-content.line-height5 {
+  line-height: 1.8em;
+}
+
+#moz-reader-content.line-height6 {
+  line-height: 2.0em;
+}
+
+#moz-reader-content.line-height7 {
+  line-height: 2.2em;
+}
+
+#moz-reader-content.line-height8 {
+  line-height: 2.4em;
+}
+
+#moz-reader-content.line-height9 {
+  line-height: 2.6em;
+}
+
+@media print {
+  #moz-reader-content p,
+  #moz-reader-content code,
+  #moz-reader-content pre,
+  #moz-reader-content blockquote,
+  #moz-reader-content ul,
+  #moz-reader-content ol,
+  #moz-reader-content li,
+  #moz-reader-content figure,
+  #moz-reader-content .wp-caption {
+    margin: 0 0 10px 0 !important;
+    padding: 0 !important;
+  }
+}
+
+#moz-reader-content h1,
+#moz-reader-content h2,
+#moz-reader-content h3 {
+  font-weight: bold;
+}
+
+#moz-reader-content h1 {
+  font-size: 1.6em;
+  line-height: 1.25em;
+}
+
+#moz-reader-content h2 {
+  font-size: 1.2em;
+  line-height: 1.51em;
+}
+
+#moz-reader-content h3 {
+  font-size: 1em;
+  line-height: 1.66em;
+}
+
+#moz-reader-content a:link {
+  text-decoration: underline;
+  font-weight: normal;
+}
+
+#moz-reader-content a:link,
+#moz-reader-content a:link:hover,
+#moz-reader-content a:link:active {
+  color: #0095dd;
+}
+
+#moz-reader-content a:visited {
+  color: #c2e;
+}
+
+#moz-reader-content * {
+  max-width: 100%;
+  height: auto;
+}
+
+#moz-reader-content p,
+#moz-reader-content p,
+#moz-reader-content code,
+#moz-reader-content pre,
+#moz-reader-content blockquote,
+#moz-reader-content ul,
+#moz-reader-content ol,
+#moz-reader-content li,
+#moz-reader-content figure,
+#moz-reader-content .wp-caption {
+  margin: -10px -10px 20px -10px;
+  padding: 10px;
+  border-radius: 5px;
+}
+
+#moz-reader-content li {
+  margin-bottom: 0;
+}
+
+#moz-reader-content li > ul,
+#moz-reader-content li > ol {
+  margin-bottom: -10px;
+}
+
+#moz-reader-content p > img:only-child,
+#moz-reader-content p > a:only-child > img:only-child,
+#moz-reader-content .wp-caption img,
+#moz-reader-content figure img {
+  display: block;
+}
+
+#moz-reader-content img[moz-reader-center] {
+  margin-left: auto;
+  margin-right: auto;
+}
+
+#moz-reader-content .caption,
+#moz-reader-content .wp-caption-text
+#moz-reader-content figcaption {
+  font-size: 0.9em;
+  line-height: 1.48em;
+  font-style: italic;
+}
+
+#moz-reader-content code,
+#moz-reader-content pre {
+  white-space: pre-wrap;
+}
+
+#moz-reader-content blockquote {
+  padding: 0;
+  padding-inline-start: 16px;
+}
+
+#moz-reader-content ul,
+#moz-reader-content ol {
+  padding: 0;
+}
+
+#moz-reader-content ul {
+  padding-inline-start: 30px;
+  list-style: disc;
+}
+
+#moz-reader-content ol {
+  padding-inline-start: 30px;
+  list-style: decimal;
+}
+
+/* Hide elements with common "hidden" class names */
+#moz-reader-content .visually-hidden,
+#moz-reader-content .visuallyhidden,
+#moz-reader-content .hidden,
+#moz-reader-content .invisible,
+#moz-reader-content .sr-only {
+  display: none;
+}
diff --git a/toolkit/themes/shared/aboutReaderContent.css b/toolkit/themes/shared/aboutReaderContent.css
deleted file mode 100644
index f69c17bf88a4..000000000000
--- a/toolkit/themes/shared/aboutReaderContent.css
+++ /dev/null
@@ -1,178 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#moz-reader-content {
-  display: none;
-  font-size: 1em;
-  line-height: 1.6em;
-}
-
-#moz-reader-content.line-height1 {
-  line-height: 1em;
-}
-
-#moz-reader-content.line-height2 {
-  line-height: 1.2em;
-}
-
-#moz-reader-content.line-height3 {
-  line-height: 1.4em;
-}
-
-#moz-reader-content.line-height4 {
-  line-height: 1.6em;
-}
-
-#moz-reader-content.line-height5 {
-  line-height: 1.8em;
-}
-
-#moz-reader-content.line-height6 {
-  line-height: 2.0em;
-}
-
-#moz-reader-content.line-height7 {
-  line-height: 2.2em;
-}
-
-#moz-reader-content.line-height8 {
-  line-height: 2.4em;
-}
-
-#moz-reader-content.line-height9 {
-  line-height: 2.6em;
-}
-
-@media print {
-  p,
-  code,
-  pre,
-  blockquote,
-  ul,
-  ol,
-  li,
-  figure,
-  .wp-caption {
-    margin: 0 0 10px 0 !important;
-    padding: 0 !important;
-  }
-}
-
-h1,
-h2,
-h3 {
-  font-weight: bold;
-}
-
-h1 {
-  font-size: 1.6em;
-  line-height: 1.25em;
-}
-
-h2 {
-  font-size: 1.2em;
-  line-height: 1.51em;
-}
-
-h3 {
-  font-size: 1em;
-  line-height: 1.66em;
-}
-
-a:link {
-  text-decoration: underline;
-  font-weight: normal;
-}
-
-a:link,
-a:link:hover,
-a:link:active {
-  color: #0095dd;
-}
-
-a:visited {
-  color: #c2e;
-}
-
-* {
-  max-width: 100%;
-  height: auto;
-}
-
-p,
-code,
-pre,
-blockquote,
-ul,
-ol,
-li,
-figure,
-.wp-caption {
-  margin: -10px -10px 20px -10px;
-  padding: 10px;
-  border-radius: 5px;
-}
-
-li {
-  margin-bottom: 0;
-}
-
-li > ul,
-li > ol {
-  margin-bottom: -10px;
-}
-
-p > img:only-child,
-p > a:only-child > img:only-child,
-.wp-caption img,
-figure img {
-  display: block;
-}
-
-img[moz-reader-center] {
-  margin-left: auto;
-  margin-right: auto;
-}
-
-.caption,
-.wp-caption-text,
-figcaption {
-  font-size: 0.9em;
-  line-height: 1.48em;
-  font-style: italic;
-}
-
-code,
-pre {
-  white-space: pre-wrap;
-}
-
-blockquote {
-  padding: 0;
-  padding-inline-start: 16px;
-}
-
-ul,
-ol {
-  padding: 0;
-}
-
-ul {
-  padding-inline-start: 30px;
-  list-style: disc;
-}
-
-ol {
-  padding-inline-start: 30px;
-  list-style: decimal;
-}
-
-/* Hide elements with common "hidden" class names */
-.visually-hidden,
-.visuallyhidden,
-.hidden,
-.invisible,
-.sr-only {
-  display: none;
-}
diff --git a/toolkit/themes/shared/aboutReaderControls.css b/toolkit/themes/shared/aboutReaderControls.css
deleted file mode 100644
index 2a4b66e5414a..000000000000
--- a/toolkit/themes/shared/aboutReaderControls.css
+++ /dev/null
@@ -1,394 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-.light-button {
-  color: #333333;
-  background-color: #ffffff;
-}
-
-.dark-button {
-  color: #eeeeee;
-  background-color: #333333;
-}
-
-.sepia-button {
-  color: #5b4636;
-  background-color: #f4ecd8;
-}
-
-.sans-serif-button {
-  font-family: Helvetica, Arial, sans-serif;
-}
-
-.serif-button {
-  font-family: Georgia, "Times New Roman", serif;
-}
-
-/* Loading/error message */
-
-#reader-message {
-  margin-top: 40px;
-  display: none;
-  text-align: center;
-  width: 100%;
-  font-size: 0.9em;
-}
-
-/* Header */
-
-.header {
-  text-align: start;
-  display: none;
-}
-
-.domain {
-  font-size: 0.9em;
-  line-height: 1.48em;
-  padding-bottom: 4px;
-  font-family: Helvetica, Arial, sans-serif;
-  text-decoration: none;
-  border-bottom: 1px solid;
-  color: #0095dd;
-}
-
-.header > h1 {
-  font-size: 1.6em;
-  line-height: 1.25em;
-  width: 100%;
-  margin: 30px 0;
-  padding: 0;
-}
-
-.header > .credits {
-  font-size: 0.9em;
-  line-height: 1.48em;
-  margin: 0 0 10px 0;
-  padding: 0;
-  font-style: italic;
-}
-
-.header > .meta-data {
-  font-size: 0.65em;
-  margin: 0 0 15px 0;
-}
-
-/*======= Controls toolbar =======*/
-
-.toolbar {
-  font-family: Helvetica, Arial, sans-serif;
-  position: fixed;
-  height: 100%;
-  top: 0;
-  left: 0;
-  margin: 0;
-  padding: 0;
-  list-style: none;
-  background-color: #fbfbfb;
-  -moz-user-select: none;
-  border-right: 1px solid #b5b5b5;
-  z-index: 1;
-}
-
-.button {
-  display: block;
-  background-size: 24px 24px;
-  background-repeat: no-repeat;
-  color: #333;
-  background-color: #fbfbfb;
-  height: 40px;
-  padding: 0;
-}
-
-.toolbar .button {
-  width: 40px;
-  background-position: center;
-  margin-right: -1px;
-  border-top: 0;
-  border-left: 0;
-  border-right: 1px solid #b5b5b5;
-  border-bottom: 1px solid #c1c1c1;
-}
-
-.button[hidden] {
-  display: none;
-}
-
-.dropdown {
-  text-align: center;
-  list-style: none;
-  margin: 0;
-  padding: 0;
-}
-
-.dropdown li {
-  margin: 0;
-  padding: 0;
-}
-
-/*======= Popup =======*/
-
-.dropdown-popup {
-  min-width: 300px;
-  text-align: start;
-  position: absolute;
-  left: 48px; /* offset to account for toolbar width */
-  z-index: 1000;
-  background-color: #fbfbfb;
-  visibility: hidden;
-  border-radius: 4px;
-  border: 1px solid #b5b5b5;
-  border-bottom-width: 0;
-  box-shadow: 0 1px 3px #c1c1c1;
-}
-
-.keep-open .dropdown-popup {
-  z-index: initial;
-}
-
-.dropdown-popup > hr {
-  display: none;
-}
-
-.open > .dropdown-popup {
-  visibility: visible;
-}
-
-.dropdown-arrow {
-  position: absolute;
-  top: 30px; /* offset arrow from top of popup */
-  left: -16px;
-  width: 16px;
-  height: 24px;
-  background-image: url("chrome://global/skin/reader/RM-Type-Controls-Arrow.svg");
-  display: block;
-}
-
-/*======= Font style popup =======*/
-
-#font-type-buttons,
-#font-size-buttons,
-#color-scheme-buttons,
-#content-width-buttons,
-#line-height-buttons {
-  display: flex;
-  flex-direction: row;
-}
-
-#font-type-buttons > button:first-child {
-  border-top-left-radius: 3px;
-}
-#font-type-buttons > button:last-child {
-  border-top-right-radius: 3px;
-}
-#color-scheme-buttons > button:first-child {
-  border-bottom-left-radius: 3px;
-}
-#color-scheme-buttons > button:last-child {
-  border-bottom-right-radius: 3px;
-}
-
-#font-type-buttons > button,
-#font-size-buttons > button,
-#color-scheme-buttons > button,
-#content-width-buttons > button,
-#line-height-buttons > button {
-  text-align: center;
-  border: 0;
-}
-
-#font-type-buttons > button,
-#font-size-buttons > button,
-#content-width-buttons > button,
-#line-height-buttons > button {
-  width: 50%;
-  background-color: transparent;
-  border-left: 1px solid #B5B5B5;
-  border-bottom: 1px solid #B5B5B5;
-}
-
-#color-scheme-buttons > button {
-  width: 33.33%;
-  font-size: 14px;
-}
-
-#color-scheme-buttons > .dark-button {
-  margin-top: -1px;
-  height: 61px;
-}
-
-#font-type-buttons > button:first-child,
-#font-size-buttons > button:first-child,
-#content-width-buttons > button:first-child,
-#line-height-buttons > button:first-child {
-  border-left: 0;
-}
-
-#font-type-buttons > button {
-  display: inline-block;
-  font-size: 62px;
-  height: 100px;
-}
-
-#font-size-buttons > button,
-#color-scheme-buttons > button,
-#content-width-buttons > button,
-#line-height-buttons > button {
-  height: 60px;
-}
-
-#font-type-buttons > button:active:hover,
-#font-type-buttons > button.selected,
-#color-scheme-buttons > button:active:hover,
-#color-scheme-buttons > button.selected {
-  box-shadow: inset 0 -3px 0 0 #fc6420;
-}
-
-#font-type-buttons > button:active:hover,
-#font-type-buttons > button.selected {
-  border-bottom: 1px solid #FC6420;
-}
-
-/* Make the serif button content the same size as the sans-serif button content. */
-#font-type-buttons > button > .description {
-  color: #666;
-  font-size: 12px;
-  margin-top: -5px;
-}
-
-/* Font sizes are different per-platform, so we need custom CSS to line them up. */
-%ifdef XP_MACOSX
-#font-type-buttons > .sans-serif-button > .name {
-  margin-top: 10px;
-}
-
-#font-type-buttons > .sans-serif-button > .description {
-  margin-top: -4px;
-}
-
-#font-type-buttons > .serif-button > .name {
-  font-size: 63px;
-}
-%elifdef XP_WIN
-#font-type-buttons > .sans-serif-button > .name {
-  margin-top: 2px;
-}
-
-#font-type-buttons > .sans-serif-button > .description {
-  margin-top: -4px;
-}
-
-#font-type-buttons > .serif-button > .name {
-  font-size: 63px;
-}
-%else
-#font-type-buttons > .sans-serif-button > .name {
-  margin-top: 5px;
-}
-
-#font-type-buttons > .sans-serif-button > .description {
-  margin-top: -8px;
-}
-
-#font-type-buttons > .serif-button > .name {
-  font-size: 70px;
-}
-%endif
-
-.button:hover,
-#font-size-buttons > button:hover,
-#font-type-buttons > button:hover,
-#content-width-buttons > button:hover,
-#line-height-buttons > button:hover {
-  background-color: #ebebeb;
-}
-
-.dropdown.open,
-.button:active,
-#font-size-buttons > button:active,
-#font-size-buttons > button.selected,
-#content-width-buttons > button:active,
-#content-width-buttons > button.selected,
-#line-height-buttons > button:active,
-#line-height-buttons > button.selected {
-  background-color: #dadada;
-}
-
-/* Only used on Android */
-#font-size-sample {
-  display: none;
-}
-
-.minus-button,
-.plus-button,
-.content-width-minus-button,
-.content-width-plus-button,
-.line-height-minus-button,
-.line-height-plus-button {
-  background-color: transparent;
-  border: 0;
-  background-size: 18px 18px;
-  background-repeat: no-repeat;
-  background-position: center;
-}
-
-/*======= Toolbar icons =======*/
-
-.close-button {
-  background-image: url("chrome://global/skin/reader/RM-Close-24x24.svg");
-  -moz-context-properties: fill;
-  fill: #808080;
-  height: 68px;
-  background-position: center 8px;
-}
-
-.close-button:hover {
-  fill: #fff;
-  background-color: #d94141;
-  border-bottom: 1px solid #d94141;
-  border-right: 1px solid #d94141;
-}
-
-.close-button:hover:active {
-  background-color: #AE2325;
-  border-bottom: 1px solid #AE2325;
-  border-right: 1px solid #AE2325;
-}
-
-.style-button {
-  background-image: url("chrome://global/skin/reader/RM-Type-Controls-24x24.svg");
-}
-
-.minus-button {
-  background-image: url("chrome://global/skin/reader/RM-Minus-24x24.svg");
-}
-
-.plus-button {
-  background-image: url("chrome://global/skin/reader/RM-Plus-24x24.svg");
-}
-
-.content-width-minus-button {
-  background-size: 42px 16px;
-  background-image: url("chrome://global/skin/reader/RM-Content-Width-Minus-42x16.svg");
-}
-
-.content-width-plus-button {
-  background-size: 44px 16px;
-  background-image: url("chrome://global/skin/reader/RM-Content-Width-Plus-44x16.svg");
-}
-
-.line-height-minus-button {
-  background-size: 34px 14px;
-  background-image: url("chrome://global/skin/reader/RM-Line-Height-Minus-38x14.svg");
-}
-
-.line-height-plus-button {
-  background-size: 34px 24px;
-  background-image: url("chrome://global/skin/reader/RM-Line-Height-Plus-38x24.svg");
-}
-
-@media print {
-  .toolbar {
-    display: none !important;
-  }
-}
diff --git a/toolkit/themes/shared/jar.inc.mn b/toolkit/themes/shared/jar.inc.mn
index a54038e2cb55..5bc40f3b7784 100644
--- a/toolkit/themes/shared/jar.inc.mn
+++ b/toolkit/themes/shared/jar.inc.mn
@@ -15,9 +15,7 @@ toolkit.jar:
   skin/classic/global/aboutCache.css                       (../../shared/aboutCache.css)
   skin/classic/global/aboutCacheEntry.css                  (../../shared/aboutCacheEntry.css)
   skin/classic/global/aboutMemory.css                      (../../shared/aboutMemory.css)
-  skin/classic/global/aboutReader.css                      (../../shared/aboutReader.css)
-  skin/classic/global/aboutReaderContent.css               (../../shared/aboutReaderContent.css)
-* skin/classic/global/aboutReaderControls.css              (../../shared/aboutReaderControls.css)
+* skin/classic/global/aboutReader.css                      (../../shared/aboutReader.css)
   skin/classic/global/aboutRights.css                      (../../shared/aboutRights.css)
   skin/classic/global/aboutLicense.css                     (../../shared/aboutLicense.css)
   skin/classic/global/aboutSupport.css                     (../../shared/aboutSupport.css)
@@ -50,7 +48,6 @@ toolkit.jar:
   skin/classic/global/icons/blocked.svg                    (../../shared/incontent-icons/blocked.svg)
   skin/classic/global/illustrations/about-license.svg      (../../shared/illustrations/about-license.svg)
   skin/classic/global/narrate.css                          (../../shared/narrate.css)
-  skin/classic/global/narrateControls.css                  (../../shared/narrateControls.css)
   skin/classic/global/narrate/arrow.svg                    (../../shared/narrate/arrow.svg)
   skin/classic/global/narrate/back.svg                     (../../shared/narrate/back.svg)
   skin/classic/global/narrate/fast.svg                     (../../shared/narrate/fast.svg)
diff --git a/toolkit/themes/shared/narrate.css b/toolkit/themes/shared/narrate.css
index 4514eff35e2d..bafdab8deec4 100644
--- a/toolkit/themes/shared/narrate.css
+++ b/toolkit/themes/shared/narrate.css
@@ -44,3 +44,190 @@ body.sepia .narrate-word-highlight {
 body.dark .narrate-word-highlight {
   border-bottom-color: #6f6f6f;
 }
+
+#narrate-dropdown {
+  --border-color: #e5e5e5;
+}
+
+#narrate-toggle > svg {
+  display: block;
+  margin: 0 8px;
+}
+
+.dropdown-popup button {
+  background-color: transparent;
+}
+
+.dropdown-popup button:hover:not(:disabled) {
+  background-color: #eaeaea;
+}
+
+.narrate-row {
+  display: flex;
+  align-items: center;
+  min-height: 40px;
+  box-sizing: border-box;
+}
+
+.narrate-row:not(:first-child) {
+  border-top: 1px solid var(--border-color);
+}
+
+/* Control buttons */
+
+#narrate-control > button {
+  background-size: 24px 24px;
+  background-repeat: no-repeat;
+  background-position: center center;
+  height: 64px;
+  width: 100px;
+  border: none;
+  color: #666;
+  box-sizing: border-box;
+}
+
+#narrate-control > button:not(:first-child) {
+  border-left: 1px solid var(--border-color);
+}
+
+#narrate-skip-previous {
+  border-top-left-radius: 3px;
+  background-image: url("chrome://global/skin/narrate/back.svg");
+  -moz-context-properties: fill;
+  fill: rgb(128 128 128);
+}
+
+#narrate-skip-next {
+  border-top-right-radius: 3px;
+  background-image: url("chrome://global/skin/narrate/forward.svg");
+  -moz-context-properties: fill;
+  fill: rgb(128 128 128);
+}
+
+#narrate-skip-previous:disabled,
+#narrate-skip-next:disabled {
+  fill: rgb(128 128 128 / 50%);
+}
+
+#narrate-start-stop {
+  background-image: url("chrome://global/skin/narrate/start.svg");
+}
+
+#narrate-dropdown.speaking #narrate-start-stop {
+  background-image: url("chrome://global/skin/narrate/stop.svg");
+}
+
+/* Rate control */
+
+#narrate-rate::before, #narrate-rate::after {
+  content: '';
+  width: 48px;
+  height: 40px;
+  background-position: center;
+  background-repeat: no-repeat;
+  background-size: 24px auto;
+}
+
+#narrate-rate::before {
+  background-image: url("chrome://global/skin/narrate/slow.svg");
+}
+
+#narrate-rate::after {
+  background-image: url("chrome://global/skin/narrate/fast.svg");
+}
+
+#narrate-rate-input {
+  margin: 0 1px;
+  flex-grow: 1;
+}
+
+#narrate-rate-input::-moz-range-track {
+  background-color: #979797;
+  height: 2px;
+}
+
+#narrate-rate-input::-moz-range-progress {
+  background-color: #2EA3FF;
+  height: 2px;
+}
+
+#narrate-rate-input::-moz-range-thumb {
+  background-color: #808080;
+  height: 16px;
+  width: 16px;
+  border-radius: 8px;
+  border-width: 0;
+}
+
+#narrate-rate-input:active::-moz-range-thumb {
+  background-color: #2EA3FF;
+}
+
+/* Voice selection */
+
+.voiceselect {
+  width: 100%;
+}
+
+.voiceselect > button.select-toggle,
+.voiceselect > .options > button.option {
+  -moz-appearance: none;
+  border: none;
+  width: 100%;
+  min-height: 40px;
+}
+
+.voiceselect.open > button.select-toggle {
+  border-bottom: 1px solid var(--border-color);
+}
+
+.voiceselect > button.select-toggle::after {
+  content: '';
+  background-image: url("chrome://global/skin/narrate/arrow.svg");
+  background-position: center;
+  background-repeat: no-repeat;
+  background-size: 12px 12px;
+  display: inline-block;
+  width: 1.5em;
+  height: 1em;
+  vertical-align: middle;
+}
+
+.voiceselect > .options > button.option:not(:first-child) {
+  border-top: 1px solid var(--border-color);
+}
+
+.voiceselect > .options > button.option  {
+  box-sizing: border-box;
+}
+
+.voiceselect > .options:not(.hovering) > button.option:focus {
+  background-color: #eaeaea;
+}
+
+.voiceselect > .options:not(.hovering) > button.option:hover:not(:focus) {
+  background-color: transparent;
+}
+
+.voiceselect > .options > button.option::-moz-focus-inner {
+  outline: none;
+  border: 0;
+}
+
+.voiceselect > .options {
+  display: none;
+  overflow-y: auto;
+}
+
+.voiceselect.open > .options {
+  display: block;
+}
+
+.current-voice {
+  color: #7f7f7f;
+}
+
+.voiceselect:not(.open) > button,
+.voiceselect .option:last-child {
+  border-radius: 0 0 3px 3px;
+}
diff --git a/toolkit/themes/shared/narrateControls.css b/toolkit/themes/shared/narrateControls.css
deleted file mode 100644
index 4def74dc88b1..000000000000
--- a/toolkit/themes/shared/narrateControls.css
+++ /dev/null
@@ -1,186 +0,0 @@
-:scope {
-  --border-color: #e5e5e5;
-}
-
-#narrate-toggle > svg {
-  display: block;
-  margin: 0 8px;
-}
-
-.dropdown-popup button {
-  background-color: transparent;
-}
-
-.dropdown-popup button:hover:not(:disabled) {
-  background-color: #eaeaea;
-}
-
-.narrate-row {
-  display: flex;
-  align-items: center;
-  min-height: 40px;
-  box-sizing: border-box;
-}
-
-.narrate-row:not(:first-child) {
-  border-top: 1px solid var(--border-color);
-}
-
-/* Control buttons */
-
-#narrate-control > button {
-  background-size: 24px 24px;
-  background-repeat: no-repeat;
-  background-position: center center;
-  height: 64px;
-  width: 100px;
-  border: none;
-  color: #666;
-  box-sizing: border-box;
-}
-
-#narrate-control > button:not(:first-child) {
-  border-left: 1px solid var(--border-color);
-}
-
-#narrate-skip-previous {
-  border-top-left-radius: 3px;
-  background-image: url("chrome://global/skin/narrate/back.svg");
-  -moz-context-properties: fill;
-  fill: rgb(128 128 128);
-}
-
-#narrate-skip-next {
-  border-top-right-radius: 3px;
-  background-image: url("chrome://global/skin/narrate/forward.svg");
-  -moz-context-properties: fill;
-  fill: rgb(128 128 128);
-}
-
-#narrate-skip-previous:disabled,
-#narrate-skip-next:disabled {
-  fill: rgb(128 128 128 / 50%);
-}
-
-#narrate-start-stop {
-  background-image: url("chrome://global/skin/narrate/start.svg");
-}
-
-#narrate-dropdown.speaking #narrate-start-stop {
-  background-image: url("chrome://global/skin/narrate/stop.svg");
-}
-
-/* Rate control */
-
-#narrate-rate::before, #narrate-rate::after {
-  content: '';
-  width: 48px;
-  height: 40px;
-  background-position: center;
-  background-repeat: no-repeat;
-  background-size: 24px auto;
-}
-
-#narrate-rate::before {
-  background-image: url("chrome://global/skin/narrate/slow.svg");
-}
-
-#narrate-rate::after {
-  background-image: url("chrome://global/skin/narrate/fast.svg");
-}
-
-#narrate-rate-input {
-  margin: 0 1px;
-  flex-grow: 1;
-}
-
-#narrate-rate-input::-moz-range-track {
-  background-color: #979797;
-  height: 2px;
-}
-
-#narrate-rate-input::-moz-range-progress {
-  background-color: #2EA3FF;
-  height: 2px;
-}
-
-#narrate-rate-input::-moz-range-thumb {
-  background-color: #808080;
-  height: 16px;
-  width: 16px;
-  border-radius: 8px;
-  border-width: 0;
-}
-
-#narrate-rate-input:active::-moz-range-thumb {
-  background-color: #2EA3FF;
-}
-
-/* Voice selection */
-
-.voiceselect {
-  width: 100%;
-}
-
-.voiceselect > button.select-toggle,
-.voiceselect > .options > button.option {
-  -moz-appearance: none;
-  border: none;
-  width: 100%;
-  min-height: 40px;
-}
-
-.voiceselect.open > button.select-toggle {
-  border-bottom: 1px solid var(--border-color);
-}
-
-.voiceselect > button.select-toggle::after {
-  content: '';
-  background-image: url("chrome://global/skin/narrate/arrow.svg");
-  background-position: center;
-  background-repeat: no-repeat;
-  background-size: 12px 12px;
-  display: inline-block;
-  width: 1.5em;
-  height: 1em;
-  vertical-align: middle;
-}
-
-.voiceselect > .options > button.option:not(:first-child) {
-  border-top: 1px solid var(--border-color);
-}
-
-.voiceselect > .options > button.option  {
-  box-sizing: border-box;
-}
-
-.voiceselect > .options:not(.hovering) > button.option:focus {
-  background-color: #eaeaea;
-}
-
-.voiceselect > .options:not(.hovering) > button.option:hover:not(:focus) {
-  background-color: transparent;
-}
-
-.voiceselect > .options > button.option::-moz-focus-inner {
-  outline: none;
-  border: 0;
-}
-
-.voiceselect > .options {
-  display: none;
-  overflow-y: auto;
-}
-
-.voiceselect.open > .options {
-  display: block;
-}
-
-.current-voice {
-  color: #7f7f7f;
-}
-
-.voiceselect:not(.open) > button,
-.option:last-child {
-  border-radius: 0 0 3px 3px;
-}