diff --git a/css/css-pseudo/highlight-cascade/highlight-cascade-008.html b/css/css-pseudo/highlight-cascade/highlight-cascade-008.html
index 720e2f0469d056..00b35a72a662a7 100644
--- a/css/css-pseudo/highlight-cascade/highlight-cascade-008.html
+++ b/css/css-pseudo/highlight-cascade/highlight-cascade-008.html
@@ -11,7 +11,7 @@
     --background-color: green;
     --decoration-color: yellow;
   }
-  ::selection {
+  :root::selection {
     --background-color: cyan;
     --decoration-color: magenta;
   }
@@ -22,10 +22,10 @@
     text-decoration-color: var(--decoration-color, red);
   }
   span {
-    --background-color: blue;
+    --background-color: purple;
   }
   span::selection {
-    --background-color: purple;
+    --background-color: blue;
     background-color: var(--background-color, red);
   }
 </style>
diff --git a/css/css-pseudo/highlight-cascade/highlight-cascade-009.html b/css/css-pseudo/highlight-cascade/highlight-cascade-009.html
index e95de9a78156c5..f063c11d217daa 100644
--- a/css/css-pseudo/highlight-cascade/highlight-cascade-009.html
+++ b/css/css-pseudo/highlight-cascade/highlight-cascade-009.html
@@ -4,17 +4,17 @@
 <link rel="author" title="Stephen Chenney" href="mailto:schenney@chromium.org">
 <link rel="help" href="https://drafts.csswg.org/css-pseudo-4/#highlight-cascade">
 <link rel="help" href="https://github.com/w3c/csswg-drafts/issues/6641">
-<meta name="assert" content="This test verifies that custom properties used in highlight pseudos are taken from the originating element.">
+<meta name="assert" content="This test verifies that custom properties used in highlight pseudos are taken from the highlight and originating element.">
 <script src="../support/selections.js"></script>
 <link rel="stylesheet" href="../support/highlights.css">
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <style>
-  :root {
+  body {
     --background-color: green;
     --decoration-color: green;
   }
-  ::selection {
+  body::selection {
     --decoration-color: purple;
   }
   div::selection {
@@ -28,14 +28,17 @@
 <script>
     selectNodeContents(document.querySelector("body"));
 
+    const div_style = getComputedStyle(document.querySelector("div"));
     const body_selection = getComputedStyle(document.querySelector("body"), "::selection");
     const div_selection = getComputedStyle(document.querySelector("div"), "::selection");
     test(() => void assert_equals(body_selection.getPropertyValue("--background-color"), "green"),
         "body ::selection uses the originating custom property");
-    test(() => void assert_equals(body_selection.getPropertyValue("--decoration-color"), "green"),
+    test(() => void assert_equals(body_selection.getPropertyValue("--decoration-color"), "purple"),
         "body ::selection does not use its own custom property");
     test(() => void assert_equals(div_selection.getPropertyValue("--decoration-color"), "green"),
         "div::selection uses the originating element custom property");
-    test(() => void assert_equals(div_selection.getPropertyValue("--background-color"), "green"),
+    test(() => void assert_equals(div_selection.getPropertyValue("--background-color"), "blue"),
         "div::selection does not use its own custom property");
+    test(() => void assert_equals(div_style.getPropertyValue("--background-color"), "green"),
+        "div::selection properties are not present on the originating element");
 </script>
diff --git a/css/css-pseudo/highlight-cascade/highlight-cascade-011.html b/css/css-pseudo/highlight-cascade/highlight-cascade-011.html
new file mode 100644
index 00000000000000..89f200485855d3
--- /dev/null
+++ b/css/css-pseudo/highlight-cascade/highlight-cascade-011.html
@@ -0,0 +1,31 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSS Pseudo-Elements Test: highlight cascade: inheritance of custom properties</title>
+<link rel="author" title="Stephen Chenney" href="mailto:schenney@chromium.org">
+<link rel="help" href="https://drafts.csswg.org/css-pseudo-4/#highlight-cascade">
+<link rel="help" href="https://github.com/w3c/csswg-drafts/issues/6641">
+<meta name="assert" content="This test verifies that custom properties used in highlight pseudos are taken from the highlight and originating element.">
+<script src="../support/selections.js"></script>
+<link rel="stylesheet" href="../support/highlights.css">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+  :root::selection {
+    --background-color: red;
+  }
+  div::selection {
+    background-color: var(--background-color, green);
+  }
+</style>
+<body>
+  <div>Some text</div>
+</body>
+<script>
+    selectNodeContents(document.querySelector("body"));
+
+    const div_selection = getComputedStyle(document.querySelector("div"), "::selection");
+    test(() => void assert_equals(div_selection.backgroundColor, "rgb(0, 128, 0)"),
+        "div::selection does not inherit custom properties from the highlight parent");
+    test(() => void assert_equals(div_selection.getPropertyValue("--background-color"), ""),
+        "--background-color has no computed value on div::selection");
+</script>
diff --git a/css/css-pseudo/highlight-styling-001.html b/css/css-pseudo/highlight-styling-001.html
index 7fe76d19380caf..2a7bb3967af200 100644
--- a/css/css-pseudo/highlight-styling-001.html
+++ b/css/css-pseudo/highlight-styling-001.html
@@ -4,18 +4,19 @@
 <link rel="author" title="Delan Azabani" href="mailto:dazabani@igalia.com">
 <link rel="help" href="https://drafts.csswg.org/css-pseudo-4/#highlight-styling">
 <link rel="match" href="highlight-styling-001-ref.html">
-<meta name="assert" value="This test verifies that ::selection styles cannot set custom properties.">
+<meta name="assert" value="This test verifies that ::selection styles can set custom properties and they over-ride the originating element.">
 <script src="support/selections.js"></script>
 <link rel="stylesheet" href="support/highlights.css">
 <style>
     main {
+        --x: red;
         font-size: 7em;
         margin: 0.5em;
     }
     main::selection {
-        --x: red;
+        --x: green;
         color: white;
-        background-color: var(--x, green);
+        background-color: var(--x, blue);
     }
 </style>
 <p>Test passes if the text below is white on green.
