diff --git a/testing/web-platform/tests/css/css-rhythm/zero-outer-size-rounded-up-to-block-step-size.html b/testing/web-platform/tests/css/css-rhythm/zero-outer-size-rounded-up-to-block-step-size.html
new file mode 100644
index 000000000000..2d77b767f52d
--- /dev/null
+++ b/testing/web-platform/tests/css/css-rhythm/zero-outer-size-rounded-up-to-block-step-size.html
@@ -0,0 +1,232 @@
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