diff --git a/testing/web-platform/tests/html/rendering/replaced-elements/images/img-sizes-auto.html b/testing/web-platform/tests/html/rendering/replaced-elements/images/img-sizes-auto.html
new file mode 100644
index 0000000000000..3865aa4561385
--- /dev/null
+++ b/testing/web-platform/tests/html/rendering/replaced-elements/images/img-sizes-auto.html
@@ -0,0 +1,393 @@
+<
+!
+doctype
+html
+>
+<
+title
+>
+default
+styles
+for
+&
+lt
+;
+img
+sizes
+=
+auto
+>
+<
+/
+title
+>
+<
+meta
+name
+=
+"
+viewport
+"
+content
+=
+"
+width
+=
+device
+-
+width
+"
+>
+<
+script
+src
+=
+"
+/
+resources
+/
+testharness
+.
+js
+"
+>
+<
+/
+script
+>
+<
+script
+src
+=
+"
+/
+resources
+/
+testharnessreport
+.
+js
+"
+>
+<
+/
+script
+>
+<
+script
+src
+=
+"
+/
+html
+/
+rendering
+/
+support
+/
+test
+-
+ua
+-
+stylesheet
+.
+js
+"
+>
+<
+/
+script
+>
+<
+style
+>
+/
+*
+Specify
+this
+bogus
+namespace
+so
+the
+rules
+in
+this
+stylesheet
+only
+apply
+to
+the
+fakeClone
+d
+elements
+in
+#
+refs
+not
+the
+HTML
+elements
+in
+#
+tests
+.
+*
+/
+namespace
+url
+(
+urn
+:
+not
+-
+html
+)
+;
+img
+:
+is
+(
+[
+sizes
+=
+"
+auto
+"
+i
+]
+[
+sizes
+^
+=
+"
+auto
+"
+i
+]
+)
+{
+contain
+:
+size
+!
+important
+;
+contain
+-
+intrinsic
+-
+size
+:
+300px
+150px
+;
+}
+<
+/
+style
+>
+<
+style
+>
+/
+*
+Test
+!
+important
+*
+/
+img
+.
+test
+-
+important
+{
+contain
+:
+style
+;
+contain
+-
+intrinsic
+-
+size
+:
+30px
+15px
+;
+}
+<
+/
+style
+>
+<
+div
+id
+=
+"
+log
+"
+>
+<
+/
+div
+>
+<
+div
+id
+=
+"
+tests
+"
+>
+<
+img
+sizes
+=
+auto
+>
+<
+img
+sizes
+=
+auto
+width
+=
+10
+height
+=
+20
+>
+<
+img
+sizes
+=
+AuTo
+>
+<
+img
+sizes
+=
+auto
+xyz
+>
+<
+img
+sizes
+=
+AuTo
+xyz
+>
+<
+!
+-
+-
+UA
+style
+should
+not
+apply
+:
+-
+-
+>
+<
+img
+>
+<
+img
+sizes
+>
+<
+img
+sizes
+=
+xyz
+auto
+>
+<
+picture
+data
+-
+skip
+>
+<
+source
+data
+-
+skip
+sizes
+=
+auto
+>
+<
+img
+>
+<
+/
+picture
+>
+<
+!
+-
+-
+Test
+!
+important
+-
+-
+>
+<
+img
+sizes
+=
+auto
+class
+=
+test
+-
+important
+>
+<
+/
+div
+>
+<
+div
+id
+=
+"
+refs
+"
+>
+<
+/
+div
+>
+<
+script
+>
+const
+props
+=
+[
+'
+contain
+'
+'
+contain
+-
+intrinsic
+-
+size
+'
+]
+;
+runUAStyleTests
+(
+props
+)
+;
+<
+/
+script
+>