| <!DOCTYPE html> |
| <title>CSS Anchor Positioning: basic last successful position fallback</title> |
| <link rel="help" href="https://drafts.csswg.org/css-anchor-position/#last-successful-position-fallback"> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <script src="support/test-common.js"></script> |
| <style> |
| #container { |
| position: relative; |
| width: 400px; |
| height: 400px; |
| background: teal; |
| } |
| #anchor { |
| position: relative; |
| top: 100px; |
| left: 100px; |
| width: 100px; |
| height: 100px; |
| background: red; |
| anchor-name: --a; |
| } |
| #anchored { |
| position-anchor: --a; |
| position-try-fallbacks: flip-block; |
| position: absolute; |
| width: 100px; |
| height: 200px; |
| position-area: top center; |
| background: lime; |
| } |
| </style> |
| <div id="container"> |
| <div id="anchor"></div> |
| <div id="anchored"></div> |
| </div> |
| <script> |
| promise_test(async () => { |
| await waitUntilNextAnimationFrame(); |
| await waitUntilNextAnimationFrame(); |
| assert_equals(anchored.offsetTop, 200); |
| }, "Starts rendering with flip-block"); |
| |
| promise_test(async () => { |
| anchor.style.top = "150px"; |
| await waitUntilNextAnimationFrame(); |
| await waitUntilNextAnimationFrame(); |
| assert_equals(anchored.offsetTop, 200); |
| }, "No successful position, keep flip-block"); |
| |
| promise_test(async () => { |
| anchor.style.top = "200px"; |
| await waitUntilNextAnimationFrame(); |
| await waitUntilNextAnimationFrame(); |
| assert_equals(anchored.offsetTop, 0); |
| }, "Base position without fallback now successful"); |
| </script> |
