<!DOCTYPE html> <link rel="help" href="https://drafts.css-houdini.org/css-layout-api/#valdef-display-layout"> <meta name="assert" content="This test checks that a layout() function works correctly with an @supports rule." /> <script src="/resources/testharness.js"></script> <script src="/resources/testharnessreport.js"></script> <style> #test { content: 'fail'; } @supports (display: layout(foo)) { #test { content: 'pass'; } } </style> <div id="test"></div> <script> test(function() { const element = document.getElementById('test'); assert_equals(getComputedStyle(element).content, '"pass"'); }); </script>