deleted file mode 100644
--- a/testing/web-platform/tests/resources/testharness.css
+++ /dev/null
@@ -1,102 +0,0 @@
-html {
-    font-family:DejaVu Sans, Bitstream Vera Sans, Arial, Sans;
-}
-
-#log .warning,
-#log .warning a {
-  color: black;
-  background: yellow;
-}
-
-#log .error,
-#log .error a {
-  color: white;
-  background: red;
-}
-
-section#summary {
-    margin-bottom:1em;
-}
-
-table#results {
-    border-collapse:collapse;
-    table-layout:fixed;
-    width:100%;
-}
-
-table#results th:first-child,
-table#results td:first-child {
-    width:4em;
-}
-
-table#results th:last-child,
-table#results td:last-child {
-    width:50%;
-}
-
-table#results.assertions th:last-child,
-table#results.assertions td:last-child {
-    width:35%;
-}
-
-table#results th {
-    padding:0;
-    padding-bottom:0.5em;
-    border-bottom:medium solid black;
-}
-
-table#results td {
-    padding:1em;
-    padding-bottom:0.5em;
-    border-bottom:thin solid black;
-}
-
-tr.pass > td:first-child {
-    color:green;
-}
-
-tr.fail > td:first-child {
-    color:red;
-}
-
-tr.timeout > td:first-child {
-    color:red;
-}
-
-tr.notrun > td:first-child {
-    color:blue;
-}
-
-.pass > td:first-child, .fail > td:first-child, .timeout > td:first-child, .notrun > td:first-child {
-    font-variant:small-caps;
-}
-
-table#results span {
-    display:block;
-}
-
-table#results span.expected {
-    font-family:DejaVu Sans Mono, Bitstream Vera Sans Mono, Monospace;
-    white-space:pre;
-}
-
-table#results span.actual {
-    font-family:DejaVu Sans Mono, Bitstream Vera Sans Mono, Monospace;
-    white-space:pre;
-}
-
-span.ok {
-    color:green;
-}
-
-tr.error {
-    color:red;
-}
-
-span.timeout {
-    color:red;
-}
-
-span.ok, span.timeout, span.error {
-    font-variant:small-caps;
-}
\ No newline at end of file

--- a/testing/web-platform/tests/resources/testharness.js
+++ b/testing/web-platform/tests/resources/testharness.js
@@ -2398,25 +2398,21 @@ policies and contribution forms [3].
             return;
         }
         var output_document = this.output_document;
 
         while (log.lastChild) {
             log.removeChild(log.lastChild);
         }
 
-        var harness_url = get_harness_url();
-        if (harness_url !== undefined) {
-            var stylesheet = output_document.createElementNS(xhtml_ns, "link");
-            stylesheet.setAttribute("rel", "stylesheet");
-            stylesheet.setAttribute("href", harness_url + "testharness.css");
-            var heads = output_document.getElementsByTagName("head");
-            if (heads.length) {
-                heads[0].appendChild(stylesheet);
-            }
+        var stylesheet = output_document.createElementNS(xhtml_ns, "style");
+        stylesheet.textContent = stylesheetContent;
+        var heads = output_document.getElementsByTagName("head");
+        if (heads.length) {
+            heads[0].appendChild(stylesheet);
         }
 
         var status_text_harness = {};
         status_text_harness[harness_status.OK] = "OK";
         status_text_harness[harness_status.ERROR] = "Error";
         status_text_harness[harness_status.TIMEOUT] = "Timeout";
 
         var status_text = {};
@@ -2916,26 +2912,16 @@ policies and contribution forms [3].
             var matches = src && src.match(/^(.*\/|)testharness\.js$/);
             if (matches) {
                 return src;
             }
         }
         return undefined;
     }
 
-    /** Returns the URL path at which the files for testharness.js are assumed to reside (e.g., '/resources/').
-        The path is derived from inspecting the 'src' of the <script> tag that included 'testharness.js'. */
-    function get_harness_url()
-    {
-        var script_url = get_script_url();
-
-        // Exclude the 'testharness.js' file from the returned path, but '+ 1' to include the trailing slash.
-        return script_url ? script_url.slice(0, script_url.lastIndexOf('/') + 1) : undefined;
-    }
-
     function supports_post_message(w)
     {
         var supports;
         var type;
         // Given IE implements postMessage across nested iframes but not across
         // windows or tabs, you can't infer cross-origin communication from the presence
         // of postMessage on the current window object only.
         //
@@ -3004,10 +2990,118 @@ policies and contribution forms [3].
         };
 
         addEventListener("error", error_handler, false);
         addEventListener("unhandledrejection", function(e){ error_handler(e.reason); }, false);
     }
 
     test_environment.on_tests_ready();
 
+    /**
+     * Stylesheet
+     */
+     var stylesheetContent = `
+html {
+    font-family:DejaVu Sans, Bitstream Vera Sans, Arial, Sans;
+}
+
+#log .warning,
+#log .warning a {
+  color: black;
+  background: yellow;
+}
+
+#log .error,
+#log .error a {
+  color: white;
+  background: red;
+}
+
+section#summary {
+    margin-bottom:1em;
+}
+
+table#results {
+    border-collapse:collapse;
+    table-layout:fixed;
+    width:100%;
+}
+
+table#results th:first-child,
+table#results td:first-child {
+    width:4em;
+}
+
+table#results th:last-child,
+table#results td:last-child {
+    width:50%;
+}
+
+table#results.assertions th:last-child,
+table#results.assertions td:last-child {
+    width:35%;
+}
+
+table#results th {
+    padding:0;
+    padding-bottom:0.5em;
+    border-bottom:medium solid black;
+}
+
+table#results td {
+    padding:1em;
+    padding-bottom:0.5em;
+    border-bottom:thin solid black;
+}
+
+tr.pass > td:first-child {
+    color:green;
+}
+
+tr.fail > td:first-child {
+    color:red;
+}
+
+tr.timeout > td:first-child {
+    color:red;
+}
+
+tr.notrun > td:first-child {
+    color:blue;
+}
+
+.pass > td:first-child, .fail > td:first-child, .timeout > td:first-child, .notrun > td:first-child {
+    font-variant:small-caps;
+}
+
+table#results span {
+    display:block;
+}
+
+table#results span.expected {
+    font-family:DejaVu Sans Mono, Bitstream Vera Sans Mono, Monospace;
+    white-space:pre;
+}
+
+table#results span.actual {
+    font-family:DejaVu Sans Mono, Bitstream Vera Sans Mono, Monospace;
+    white-space:pre;
+}
+
+span.ok {
+    color:green;
+}
+
+tr.error {
+    color:red;
+}
+
+span.timeout {
+    color:red;
+}
+
+span.ok, span.timeout, span.error {
+    font-variant:small-caps;
+}
+`;
+
 })(this);
 // vim: set expandtab shiftwidth=4 tabstop=4: