diff --git a/media/js/base/site.js b/media/js/base/site.js
index 1b927e4165e..33942b7a562 100644
--- a/media/js/base/site.js
+++ b/media/js/base/site.js
@@ -55,22 +55,29 @@
         },
 
         // Madness from https://docs.microsoft.com/microsoft-edge/web-platform/how-to-detect-win11
+        // and https://wicg.github.io/ua-client-hints/#sec-ch-ua-platform-version
         getWindowsVersionClientHint: function (version) {
             var fullPlatformVersion = version ? version.toString() : '0';
-            var majorPlatformVersion = parseInt(
-                fullPlatformVersion.split('.')[0],
-                10
-            );
-            if (majorPlatformVersion >= 13) {
+            var platformVersion = parseFloat(fullPlatformVersion);
+
+            if (platformVersion >= 13.0) {
                 // Windows 11 or later.
-                return '11.0.0';
-            } else if (majorPlatformVersion > 0) {
+                return '11.0';
+            } else if (platformVersion >= 1.0 && platformVersion < 13.0) {
                 // Windows 10
-                return '10.0.0';
+                return '10.0';
+            } else if (platformVersion === 0.3) {
+                // Windows 8.1
+                return '6.3';
+            } else if (platformVersion === 0.2) {
+                // Windows 8
+                return '6.2';
+            } else if (platformVersion === 0.1) {
+                // Windows 7
+                return '6.1';
             } else {
-                // Might be any Windows version less than 10, who knows.
-                // Rather than return undefined here, fallback to UA string.
-                return site.getPlatformVersion();
+                // Windows versions older than 7 are not reported, so return zero.
+                return '0';
             }
         },
 
diff --git a/tests/unit/spec/base/site.js b/tests/unit/spec/base/site.js
index 547bf2dc081..bbd09517185 100644
--- a/tests/unit/spec/base/site.js
+++ b/tests/unit/spec/base/site.js
@@ -12,6 +12,12 @@
 describe('site.js', function () {
     describe('getPlatform', function () {
         it('should identify Windows', function () {
+            expect(
+                window.site.getPlatform(
+                    'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36',
+                    'Win64'
+                )
+            ).toBe('windows');
             expect(
                 window.site.getPlatform(
                     'Mozilla/5.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727)',
@@ -375,40 +381,91 @@ describe('site.js', function () {
     describe('getWindowsVersionClientHint', function () {
         it('should identify 13 and up as Windows 11 or later', function () {
             expect(window.site.getWindowsVersionClientHint('13.0.0')).toBe(
-                '11.0.0'
+                '11.0'
             );
             expect(window.site.getWindowsVersionClientHint('14.0.0')).toBe(
-                '11.0.0'
+                '11.0'
             );
         });
 
         it('should identify 1 through 12 as Windows 10', function () {
             expect(window.site.getWindowsVersionClientHint('12.0.0')).toBe(
-                '10.0.0'
+                '10.0'
+            );
+            expect(window.site.getWindowsVersionClientHint('12.1.0')).toBe(
+                '10.0'
             );
             expect(window.site.getWindowsVersionClientHint('11.0.0')).toBe(
-                '10.0.0'
+                '10.0'
             );
             expect(window.site.getWindowsVersionClientHint('10.0.0')).toBe(
-                '10.0.0'
+                '10.0'
+            );
+            expect(window.site.getWindowsVersionClientHint('9.0.0')).toBe(
+                '10.0'
+            );
+            expect(window.site.getWindowsVersionClientHint('8.0.0')).toBe(
+                '10.0'
+            );
+            expect(window.site.getWindowsVersionClientHint('7.0.0')).toBe(
+                '10.0'
+            );
+            expect(window.site.getWindowsVersionClientHint('6.0.0')).toBe(
+                '10.0'
+            );
+            expect(window.site.getWindowsVersionClientHint('5.0.0')).toBe(
+                '10.0'
+            );
+            expect(window.site.getWindowsVersionClientHint('4.0.0')).toBe(
+                '10.0'
+            );
+            expect(window.site.getWindowsVersionClientHint('3.0.0')).toBe(
+                '10.0'
+            );
+            expect(window.site.getWindowsVersionClientHint('2.0.0')).toBe(
+                '10.0'
             );
             expect(window.site.getWindowsVersionClientHint('1.0.0')).toBe(
-                '10.0.0'
+                '10.0'
+            );
+        });
+
+        it('should identify 0.3 as Windows 8.1', function () {
+            expect(window.site.getWindowsVersionClientHint('0.3')).toBe('6.3');
+            expect(window.site.getWindowsVersionClientHint('0.3.1')).toBe(
+                '6.3'
+            );
+        });
+
+        it('should identify 0.2 as Windows 8', function () {
+            expect(window.site.getWindowsVersionClientHint('0.2')).toBe('6.2');
+            expect(window.site.getWindowsVersionClientHint('0.2.0')).toBe(
+                '6.2'
             );
-            expect(window.site.getWindowsVersionClientHint('1')).toBe('10.0.0');
-            expect(window.site.getWindowsVersionClientHint(1.0)).toBe('10.0.0');
-            expect(window.site.getWindowsVersionClientHint(12)).toBe('10.0.0');
         });
 
-        it('should return fallback to using UA string for unknown Windows versions', function () {
-            spyOn(window.site, 'getPlatformVersion').and.returnValue('8.1');
+        it('should identify 0.1 as Windows 7', function () {
+            expect(window.site.getWindowsVersionClientHint('0.1')).toBe('6.1');
+            expect(window.site.getWindowsVersionClientHint('0.1.2')).toBe(
+                '6.1'
+            );
+        });
 
-            expect(window.site.getWindowsVersionClientHint('0.0.0')).toBe(
-                '8.1'
+        it('should identify 0.1 as Windows 7', function () {
+            expect(window.site.getWindowsVersionClientHint('0.1')).toBe('6.1');
+            expect(window.site.getWindowsVersionClientHint('0.1.2')).toBe(
+                '6.1'
             );
-            expect(window.site.getWindowsVersionClientHint(0.0)).toBe('8.1');
-            expect(window.site.getWindowsVersionClientHint('0')).toBe('8.1');
-            expect(window.site.getWindowsVersionClientHint('')).toBe('8.1');
+        });
+
+        it('should return anything else as zero / unknown', function () {
+            expect(window.site.getWindowsVersionClientHint('0.9')).toBe('0');
+            expect(window.site.getWindowsVersionClientHint('0.8')).toBe('0');
+            expect(window.site.getWindowsVersionClientHint('0.7')).toBe('0');
+            expect(window.site.getWindowsVersionClientHint('0.6')).toBe('0');
+            expect(window.site.getWindowsVersionClientHint('0.5')).toBe('0');
+            expect(window.site.getWindowsVersionClientHint('0.4')).toBe('0');
+            expect(window.site.getWindowsVersionClientHint('0.0.1')).toBe('0');
         });
     });