This is a testharness.js-based test.
Harness Error. harness_status.status = 1 , harness_status.message = 1 duplicate test name: "Uses of var() in CSS keyframes are responsive to changes in custom properties."
PASS Uses of var() in CSS keyframes are responsive to changes in custom properties. 
PASS Uses of var() in CSS keyframes are responsive to changes in custom properties. 
Harness: the test ran to completion.