diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-001-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-001-ref.html
new file mode 100644
index 0000000000000..299930ac35a35
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-001-ref.html
@@ -0,0 +1,14 @@
+
+
+
CSS contain-intrinsic-size: unsized div
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-001.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-001.html
new file mode 100644
index 0000000000000..86f141e0878e1
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-001.html
@@ -0,0 +1,17 @@
+
+
+CSS contain-intrinsic-size: unsized div
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-002-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-002-ref.html
new file mode 100644
index 0000000000000..a2fc6a0731be1
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-002-ref.html
@@ -0,0 +1,21 @@
+
+
+CSS contain-intrinsic-size: div with max-content parent
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-002.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-002.html
new file mode 100644
index 0000000000000..cef3ed27cee39
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-002.html
@@ -0,0 +1,23 @@
+
+
+CSS contain-intrinsic-size: div with max-content parent
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-003-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-003-ref.html
new file mode 100644
index 0000000000000..dab2739460af1
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-003-ref.html
@@ -0,0 +1,15 @@
+
+
+CSS contain-intrinsic-size: width specified
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-003.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-003.html
new file mode 100644
index 0000000000000..a56d02b316d52
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-003.html
@@ -0,0 +1,18 @@
+
+
+CSS contain-intrinsic-size: width specified
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-004-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-004-ref.html
new file mode 100644
index 0000000000000..5f896803e31c9
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-004-ref.html
@@ -0,0 +1,15 @@
+
+
+CSS contain-intrinsic-size: width is min-content
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-004.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-004.html
new file mode 100644
index 0000000000000..dd1055d768f55
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-004.html
@@ -0,0 +1,18 @@
+
+
+CSS contain-intrinsic-size: width is min-content
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-005-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-005-ref.html
new file mode 100644
index 0000000000000..0940a6f702ff3
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-005-ref.html
@@ -0,0 +1,15 @@
+
+
+CSS contain-intrinsic-size: width is max-content
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-005.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-005.html
new file mode 100644
index 0000000000000..b5f019b0423c1
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-005.html
@@ -0,0 +1,18 @@
+
+
+CSS contain-intrinsic-size: width is max-content
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-006-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-006-ref.html
new file mode 100644
index 0000000000000..9d3912dafe15c
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-006-ref.html
@@ -0,0 +1,16 @@
+
+
+CSS contain-intrinsic-size: unsized div, intrinsic-size is small
+
+
+
+
+
+Lorem ipsum
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-006.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-006.html
new file mode 100644
index 0000000000000..6dd0e47729cc2
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-006.html
@@ -0,0 +1,17 @@
+
+
+CSS contain-intrinsic-size: unsized div, intrinsic-size is small
+
+
+
+
+
+
+
+Lorem ipsum
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-007-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-007-ref.html
new file mode 100644
index 0000000000000..c372f2dfcedee
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-007-ref.html
@@ -0,0 +1,27 @@
+
+
+CSS contain-intrinsic-size: div with border
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-007.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-007.html
new file mode 100644
index 0000000000000..838836c3a9e7c
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-007.html
@@ -0,0 +1,27 @@
+
+
+CSS contain-intrinsic-size: div with border
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-008-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-008-ref.html
new file mode 100644
index 0000000000000..af20b26a39566
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-008-ref.html
@@ -0,0 +1,37 @@
+
+
+CSS contain-intrinsic-size: writing modes
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-008.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-008.html
new file mode 100644
index 0000000000000..ac265ad7b21f7
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-008.html
@@ -0,0 +1,38 @@
+
+
+CSS contain-intrinsic-size: writing modes
+
+
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-009-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-009-ref.html
new file mode 100644
index 0000000000000..7b3dc7027e6d6
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-009-ref.html
@@ -0,0 +1,23 @@
+
+
+CSS contain-intrinsic-size: select multiple
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-009.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-009.html
new file mode 100644
index 0000000000000..bc9ab46306490
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-009.html
@@ -0,0 +1,24 @@
+
+
+CSS contain-intrinsic-size: select multiple
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-010-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-010-ref.html
new file mode 100644
index 0000000000000..950ddd1f8902c
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-010-ref.html
@@ -0,0 +1,39 @@
+
+
+CSS contain-intrinsic-size: flex row
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-010.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-010.html
new file mode 100644
index 0000000000000..f5df500e8c9d2
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-010.html
@@ -0,0 +1,43 @@
+
+
+CSS contain-intrinsic-size: flex row
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-011-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-011-ref.html
new file mode 100644
index 0000000000000..68d1fbe408442
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-011-ref.html
@@ -0,0 +1,39 @@
+
+
+CSS contain-intrinsic-size: flex column
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-011.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-011.html
new file mode 100644
index 0000000000000..de35326629b4b
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-011.html
@@ -0,0 +1,43 @@
+
+
+CSS contain-intrinsic-size: flex column
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-012-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-012-ref.html
new file mode 100644
index 0000000000000..4b0fe755b487a
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-012-ref.html
@@ -0,0 +1,14 @@
+
+
+CSS contain-intrinsic-size: replaced content
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-012.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-012.html
new file mode 100644
index 0000000000000..54a49c18561fa
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-012.html
@@ -0,0 +1,16 @@
+
+
+CSS contain-intrinsic-size: replaced content
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-013-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-013-ref.html
new file mode 100644
index 0000000000000..7a0b5788aee68
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-013-ref.html
@@ -0,0 +1,18 @@
+
+
+CSS contain-intrinsic-size: intrinsic-size changes
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-013.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-013.html
new file mode 100644
index 0000000000000..370398042fd64
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-013.html
@@ -0,0 +1,33 @@
+
+
+
+CSS contain-intrinsic-size: intrinsic-size changes.
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-014-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-014-ref.html
new file mode 100644
index 0000000000000..72a24c7a5955d
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-014-ref.html
@@ -0,0 +1,18 @@
+
+
+CSS contain-intrinsic-size: fieldset
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-014.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-014.html
new file mode 100644
index 0000000000000..d268264d28f33
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-014.html
@@ -0,0 +1,20 @@
+
+
+CSS contain-intrinsic-size: fieldset
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-015-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-015-ref.html
new file mode 100644
index 0000000000000..76abf0c14bcfe
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-015-ref.html
@@ -0,0 +1,16 @@
+
+
+CSS contain-intrinsic-size: inline flex
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-015.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-015.html
new file mode 100644
index 0000000000000..8eda4b88452f0
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-015.html
@@ -0,0 +1,18 @@
+
+
+CSS contain-intrinsic-size: inline flex
+
+
+
+
+
+
+test
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-016-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-016-ref.html
new file mode 100644
index 0000000000000..029159390ac33
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-016-ref.html
@@ -0,0 +1,39 @@
+
+
+CSS contain-intrinsic-size: flex row, items with size containment (ref)
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-016.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-016.html
new file mode 100644
index 0000000000000..fabc48d4a0bdc
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-016.html
@@ -0,0 +1,44 @@
+
+
+CSS contain-intrinsic-size: flex row, items with size containment
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-017-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-017-ref.html
new file mode 100644
index 0000000000000..49f7499fe8cce
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-017-ref.html
@@ -0,0 +1,17 @@
+
+
+CSS contain-intrinsic-size: replaced content (vertical-lr)
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-017.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-017.html
new file mode 100644
index 0000000000000..5ce15eba599c7
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-017.html
@@ -0,0 +1,21 @@
+
+
+CSS contain-intrinsic-size: replaced content (vertical-lr)
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-018-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-018-ref.html
new file mode 100644
index 0000000000000..537001d6d1ba8
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-018-ref.html
@@ -0,0 +1,15 @@
+
+
+CSS contain-intrinsic-size: sized div
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-018.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-018.html
new file mode 100644
index 0000000000000..649e83364ffc1
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-018.html
@@ -0,0 +1,19 @@
+
+
+CSS contain-intrinsic-size: sized div
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-019-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-019-ref.html
new file mode 100644
index 0000000000000..172c78177b80d
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-019-ref.html
@@ -0,0 +1,15 @@
+
+
+CSS contain-intrinsic-size: div with fit-content width
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-019.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-019.html
new file mode 100644
index 0000000000000..4ba1bed9de585
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-019.html
@@ -0,0 +1,18 @@
+
+
+CSS contain-intrinsic-size: div with fit-content width
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-020-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-020-ref.html
new file mode 100644
index 0000000000000..c4f34e84f03ac
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-020-ref.html
@@ -0,0 +1,14 @@
+
+
+CSS contain-intrinsic-size: replaced content (min-content)
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-020.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-020.html
new file mode 100644
index 0000000000000..42482abf0f222
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-020.html
@@ -0,0 +1,18 @@
+
+
+CSS contain-intrinsic-size: replaced content (min-content)
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-021-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-021-ref.html
new file mode 100644
index 0000000000000..601965208716e
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-021-ref.html
@@ -0,0 +1,41 @@
+
+
+CSS contain-intrinsic-size: flex row, flex height based on children
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-021.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-021.html
new file mode 100644
index 0000000000000..12f939842045f
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-021.html
@@ -0,0 +1,42 @@
+
+
+CSS contain-intrinsic-size: flex row, flex height based on children
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-022-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-022-ref.html
new file mode 100644
index 0000000000000..81991fb17c64c
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-022-ref.html
@@ -0,0 +1,30 @@
+
+
+CSS contain-intrinsic-size: grid definite size
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-022.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-022.html
new file mode 100644
index 0000000000000..5f5885174826b
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-022.html
@@ -0,0 +1,32 @@
+
+
+CSS contain-intrinsic-size: grid definite size
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-023-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-023-ref.html
new file mode 100644
index 0000000000000..eccbecb6c0009
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-023-ref.html
@@ -0,0 +1,29 @@
+
+
+CSS contain-intrinsic-size: grid indefinite size
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-023.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-023.html
new file mode 100644
index 0000000000000..f8e3a607f1e38
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-023.html
@@ -0,0 +1,31 @@
+
+
+CSS contain-intrinsic-size: grid indefinite size
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-024-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-024-ref.html
new file mode 100644
index 0000000000000..e2f53b6570755
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-024-ref.html
@@ -0,0 +1,30 @@
+
+
+CSS contain-intrinsic-size: grid definite size, large size
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-024.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-024.html
new file mode 100644
index 0000000000000..f6305d438b3c9
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-024.html
@@ -0,0 +1,32 @@
+
+
+CSS contain-intrinsic-size: grid definite size, large size
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-025-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-025-ref.html
new file mode 100644
index 0000000000000..f760a49cbf012
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-025-ref.html
@@ -0,0 +1,53 @@
+
+
+CSS contain-intrinsic-size: grid indefinite size, auto-fit
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-025.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-025.html
new file mode 100644
index 0000000000000..5557fcc8d68a3
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-025.html
@@ -0,0 +1,58 @@
+
+
+CSS contain-intrinsic-size: grid indefinite size, auto-fit
+
+
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-026-ref.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-026-ref.html
new file mode 100644
index 0000000000000..8389ef701b2da
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-026-ref.html
@@ -0,0 +1,53 @@
+
+
+CSS contain-intrinsic-size: grid auto-fit, min- max- size interactions
+
+
+
+
+
+min-width larger than contain-intrinsic-width:
+
+
+min-width smaller than contain-intrinsic-width:
+
+
+max-width ignored since min-width is larger:
+
+
+min-width shrinks grid since it overrides contain-intrinsic-width:
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-026.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-026.html
new file mode 100644
index 0000000000000..c9f3f1aa38073
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/contain-intrinsic-size-026.html
@@ -0,0 +1,66 @@
+
+
+CSS contain-intrinsic-size: grid auto-fit, min- max- size interactions
+
+
+
+
+
+
+
+min-width larger than contain-intrinsic-width:
+
+
+min-width smaller than contain-intrinsic-width:
+
+
+max-width ignored since min-width is larger:
+
+
+min-width shrinks grid since it overrides contain-intrinsic-width:
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/parsing/contain-intrinsic-size-computed.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/parsing/contain-intrinsic-size-computed.html
new file mode 100644
index 0000000000000..68ec4fce76916
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/parsing/contain-intrinsic-size-computed.html
@@ -0,0 +1,31 @@
+
+
+
+
+CSS Intrinsic Size Test: intrinsic-size with computed values
+
+
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/parsing/contain-intrinsic-size-invalid.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/parsing/contain-intrinsic-size-invalid.html
new file mode 100644
index 0000000000000..2ee8a20a9cdfc
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/parsing/contain-intrinsic-size-invalid.html
@@ -0,0 +1,28 @@
+
+
+
+
+CSS Intrinsic Size Test: intrinsic-size with invalid values
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/parsing/contain-intrinsic-size-valid.html b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/parsing/contain-intrinsic-size-valid.html
new file mode 100644
index 0000000000000..8cd3922071b80
--- /dev/null
+++ b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/parsing/contain-intrinsic-size-valid.html
@@ -0,0 +1,22 @@
+
+
+
+
+CSS Intrinsic Size Test: intrinsic-size with valid values
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/resources/dice.png b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/resources/dice.png
new file mode 100644
index 0000000000000..c82d01517cd05
Binary files /dev/null and b/testing/web-platform/tests/css/css-sizing/contain-intrinsic-size/resources/dice.png differ