diff --git a/layout/style/res/ua.css b/layout/style/res/ua.css
index 504f5dc57..a8425d472 100644
--- a/layout/style/res/ua.css
+++ b/layout/style/res/ua.css
@@ -46,6 +46,9 @@
backface-visibility: inherit;
clip: inherit;
/* When the table wrapper is a Flex/Grid item we need these: */
+ flex-grow: inherit;
+ flex-shrink: inherit;
+ flex-basis: inherit;
align-self: inherit;
justify-self: inherit;
grid-column-start: inherit;
diff --git a/testing/web-platform/meta/css/css-flexbox/table-item-flex-percentage-width.html.ini b/testing/web-platform/meta/css/css-flexbox/table-item-flex-percentage-width.html.ini
new file mode 100644
index 000000000..8069b87eb
--- /dev/null
+++ b/testing/web-platform/meta/css/css-flexbox/table-item-flex-percentage-width.html.ini
@@ -0,0 +1,3 @@
+[table-item-flex-percentage-width.html]
+ expected: FAIL
+ bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1674268
diff --git a/testing/web-platform/tests/css/css-flexbox/table-item-flex-percentage-width-ref.html b/testing/web-platform/tests/css/css-flexbox/table-item-flex-percentage-width-ref.html
new file mode 100644
index 000000000..e598475fd
--- /dev/null
+++ b/testing/web-platform/tests/css/css-flexbox/table-item-flex-percentage-width-ref.html
@@ -0,0 +1,140 @@
+
+Reference: display:table flex items with flex-shrink/flex-grow/flex-basis
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diff --git a/testing/web-platform/tests/css/css-flexbox/table-item-flex-percentage-width.html b/testing/web-platform/tests/css/css-flexbox/table-item-flex-percentage-width.html
new file mode 100644
index 000000000..f21b5f0c6
--- /dev/null
+++ b/testing/web-platform/tests/css/css-flexbox/table-item-flex-percentage-width.html
@@ -0,0 +1,144 @@
+
+Flexbox Test: display:table flex items with flex-shrink/flex-grow/flex-basis
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