diff --git a/css/css-pseudo/active-selection-021.html b/css/css-pseudo/active-selection-021.html
new file mode 100644
index 00000000000000..2061385d6c564c
--- /dev/null
+++ b/css/css-pseudo/active-selection-021.html
@@ -0,0 +1,54 @@
+<!DOCTYPE html>
+
+  <meta charset="UTF-8">
+
+  <title>CSS Pseudo-Elements Test: active selection, color and 'text-decoration: underline overline line-through'</title>
+
+  <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
+  <link rel="help" href="https://www.w3.org/TR/css-pseudo-4/#highlight-styling">
+  <link rel="match" href="reference/active-selection-021-ref.html">
+
+  <meta content="" name="flags">
+
+  <style>
+  div
+    {
+      color: red;
+      font-size: 300%;
+      text-decoration: underline overline line-through;
+    }
+
+  div::selection
+    {
+      color: green;
+    }
+  </style>
+
+  <!--
+  "
+  The element's own text decorations (both line decorations
+  and emphasis marks) are thus drawn in the pseudo-element's
+  own color when that is not currentColor, regardless of
+  their original color or fill specifications.
+  "
+  coming from
+  https://www.w3.org/TR/css-pseudo-4/#highlight-painting
+  -->
+
+  <script>
+  function startTest()
+  {
+  var targetRange = document.createRange();
+  /* We first create an empty range */
+  targetRange.selectNodeContents(document.getElementById("test"));
+  /* Then we set the range boundaries to the children of div#test */
+  window.getSelection().addRange(targetRange);
+  /* Finally, we now select such range of content */
+  }
+  </script>
+
+  <body onload="startTest();">
+
+  <p>Test passes if each glyph of "Selected Text" is green and <strong>not red</strong> and if the underline, the overline and the line-through are also green and not red.
+
+  <div id="test">Selected Text</div>
diff --git a/css/css-pseudo/active-selection-024.html b/css/css-pseudo/active-selection-024.html
new file mode 100644
index 00000000000000..5668df550bb018
--- /dev/null
+++ b/css/css-pseudo/active-selection-024.html
@@ -0,0 +1,49 @@
+<!DOCTYPE html>
+
+  <meta charset="UTF-8">
+
+  <title>CSS Pseudo-Elements Test: active selection and first-letter pseudo-element</title>
+
+  <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
+  <link rel="help" href="https://www.w3.org/TR/css-pseudo-4/#highlight-selectors">
+  <link rel="match" href="reference/active-selection-024-ref.html">
+
+  <meta content="" name="flags">
+  <meta name="assert" content="In this test, the ::selection pseudo-element must paint over the ::first-letter pseudo-element since the first letter is being selected.">
+
+  <style>
+  div
+    {
+      color: black;
+      font-size: 300%;
+    }
+
+  div::first-letter
+    {
+      color: red;
+    }
+
+  div::selection
+    {
+      background-color: yellow;
+      color: green;
+    }
+  </style>
+
+  <script>
+  function startTest()
+  {
+  var targetRange = document.createRange();
+  /* We first create an empty range */
+  targetRange.selectNodeContents(document.getElementById("test"));
+  /* Then we set the range boundaries to the children of div#test */
+  window.getSelection().addRange(targetRange);
+  /* Finally, we now select such range of content */
+  }
+  </script>
+
+  <body onload="startTest();">
+
+  <p>Test passes if background color of "Selected Text" is yellow and if each glyph of "Selected Text" is green.
+
+  <div id="test">Selected Text</div>
diff --git a/css/css-pseudo/active-selection-031.html b/css/css-pseudo/active-selection-031.html
new file mode 100644
index 00000000000000..387bb82082f3a1
--- /dev/null
+++ b/css/css-pseudo/active-selection-031.html
@@ -0,0 +1,86 @@
+<!DOCTYPE html>
+
+  <meta charset="UTF-8">
+
+  <title>CSS Pseudo-Elements Test: active selection and vertical writing-modes</title>
+
+  <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
+  <link rel="help" href="https://www.w3.org/TR/css-pseudo-4/#highlight-styling">
+  <link rel="match" href="reference/active-selection-031-ref.html">
+
+  <meta content="" name="flags">
+
+  <style>
+  div > div
+    {
+      color: red;
+      float: left;
+      font-size: 48px;
+      margin-left: 16px;
+    }
+
+  div.vrl
+    {
+      writing-mode: vertical-rl;
+    }
+
+  div.vlr
+    {
+      writing-mode: vertical-lr;
+    }
+
+  div.mixed
+    {
+      text-orientation: mixed;
+    }
+
+  div.sideways
+    {
+      text-orientation: sideways;
+    }
+
+  div.upright
+    {
+      text-orientation: upright;
+    }
+
+  div::selection
+    {
+      background-color: yellow;
+      color: green;
+    }
+  </style>
+
+  <script>
+  function startTest()
+  {
+    var targetRange = document.createRange();
+    /* We first create an empty range */
+
+    targetRange.selectNodeContents(document.getElementById("test"));
+    /* Then we set the range boundaries to the contents of div#test */
+
+    window.getSelection().addRange(targetRange);
+    /* Finally, we now add such range of content into a selection */
+  }
+  </script>
+
+  <body onload="startTest();">
+
+  <p>Test passes if each glyph of the 6 "Selected Text" is green and if there is <strong>no red</strong>.
+
+  <div id="test">
+
+    <div class="vrl mixed">Selected Text</div>
+
+    <div class="vrl sideways">Selected Text</div>
+
+    <div class="vrl upright">Selected Text</div>
+
+    <div class="vlr mixed">Selected Text</div>
+
+    <div class="vlr sideways">Selected Text</div>
+
+    <div class="vlr upright">Selected Text</div>
+
+  </div>
diff --git a/css/css-pseudo/active-selection-045.html b/css/css-pseudo/active-selection-045.html
new file mode 100644
index 00000000000000..f5497e2e0ba2f5
--- /dev/null
+++ b/css/css-pseudo/active-selection-045.html
@@ -0,0 +1,62 @@
+<!DOCTYPE html>
+
+  <meta charset="UTF-8">
+
+  <title>CSS Pseudo-Elements Test: active selection and image</title>
+
+  <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
+  <link rel="help" href="https://www.w3.org/TR/css-pseudo-4/#highlight-painting">
+  <link rel="match" href="../reference/ref-nothing-below.xht">
+
+  <meta content="" name="flags">
+  <meta name="assert" content="This test checks that the associated overlay for image must not cover (or leak) outside the image's content box.">
+
+  <style>
+  /*
+  Chromium 80+ highlights the
+  top of line box height minus
+  content box and the bottom of
+  line box height minus content
+  box.
+  Firefox 72+ consistently highlights
+  only the image content box itself.
+  */
+
+  div
+    {
+      font-size: 300px;
+    }
+
+  img::selection
+    {
+      background-color: red;
+    }
+
+  span#masking
+    {
+      background-color: white;
+      display: inline-block;
+      height: 100px;
+      position: relative;
+      right: 100px;
+      width: 100px;
+    }
+  </style>
+
+  <script>
+  function startTest()
+  {
+  var targetRange = document.createRange();
+  /* We first create an empty range */
+  targetRange.selectNodeContents(document.getElementById("test"));
+  /* Then we set the range boundaries to the children of div#test */
+  window.getSelection().addRange(targetRange);
+  /* Finally, we now select such range of content */
+  }
+  </script>
+
+  <body onload="startTest();">
+
+  <p>Test passes if there is nothing below.
+
+  <div id="test"><img src="support/100x100-red.png" alt="Image download support must be enabled"><span id="masking"></span></div>
diff --git a/css/css-pseudo/reference/active-selection-021-ref.html b/css/css-pseudo/reference/active-selection-021-ref.html
new file mode 100644
index 00000000000000..7790a3fad8a36f
--- /dev/null
+++ b/css/css-pseudo/reference/active-selection-021-ref.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+
+  <meta charset="UTF-8">
+
+  <title>CSS Reftest Reference</title>
+
+  <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
+
+  <style>
+  div
+    {
+      color: green;
+      font-size: 300%;
+      text-decoration: underline overline line-through;
+    }
+  </style>
+
+  <p>Test passes if each glyph of "Selected Text" is green and <strong>not red</strong> and if the underline, the overline and the line-through are also green and not red.
+
+  <div>Selected Text</div>
diff --git a/css/css-pseudo/reference/active-selection-024-ref.html b/css/css-pseudo/reference/active-selection-024-ref.html
new file mode 100644
index 00000000000000..e6dda1c1371b53
--- /dev/null
+++ b/css/css-pseudo/reference/active-selection-024-ref.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+
+  <meta charset="UTF-8">
+
+  <title>CSS Reftest Reference</title>
+
+  <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
+
+  <style>
+  div
+    {
+      background-color: yellow;
+      color: green;
+      display: inline;
+      font-size: 300%;
+    }
+  </style>
+
+  <p>Test passes if background color of "Selected Text" is yellow and if each glyph of "Selected Text" is green.
+
+  <div>Selected Text</div>
diff --git a/css/css-pseudo/reference/active-selection-031-ref.html b/css/css-pseudo/reference/active-selection-031-ref.html
new file mode 100644
index 00000000000000..0e3680844f8870
--- /dev/null
+++ b/css/css-pseudo/reference/active-selection-031-ref.html
@@ -0,0 +1,57 @@
+<!DOCTYPE html>
+
+  <meta charset="UTF-8">
+
+  <title>CSS Reftest Reference</title>
+
+  <link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
+
+  <style>
+  div
+    {
+      background-color: yellow;
+      color: green;
+      float: left;
+      font-size: 48px;
+      margin-left: 16px;
+    }
+
+  div.vrl
+    {
+      writing-mode: vertical-rl;
+    }
+
+  div.vlr
+    {
+      writing-mode: vertical-lr;
+    }
+
+  div.mixed
+    {
+      text-orientation: mixed;
+    }
+
+  div.sideways
+    {
+      text-orientation: sideways;
+    }
+
+  div.upright
+    {
+      text-orientation: upright;
+    }
+  </style>
+
+  <p>Test passes if each glyph of the 6 "Selected Text" is green and if there is <strong>no red</strong>.
+
+  <div class="vrl mixed">Selected Text</div>
+
+  <div class="vrl sideways">Selected Text</div>
+
+  <div class="vrl upright">Selected Text</div>
+
+  <div class="vlr mixed">Selected Text</div>
+
+  <div class="vlr sideways">Selected Text</div>
+
+  <div class="vlr upright">Selected Text</div>
diff --git a/css/css-pseudo/support/100x100-red.png b/css/css-pseudo/support/100x100-red.png
new file mode 100644
index 00000000000000..57bf3ddc5213d0
Binary files /dev/null and b/css/css-pseudo/support/100x100-red.png differ
