| <!DOCTYPE html> |
| <title>CSS Transitions Test: @starting-style inside size @container</title> |
| <link rel="help" href="https://drafts.csswg.org/css-transitions-2/#defining-before-change-style-the-starting-style-rule"> |
| <link rel="help" href="https://drafts.csswg.org/css-contain-3/#animated-containers"> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <script src="/css/css-transitions/support/helper.js"></script> |
| <div id="container" style="width: 200px"> |
| <div id="target" style="display: none"></div> |
| </div> |
| <style> |
| #container { |
| container-type: inline-size; |
| } |
| #target { |
| transition-property: background-color; |
| transition-duration: 100s; |
| transition-timing-function: steps(2, start); |
| background-color: lime; |
| } |
| @container (width > 300px) { |
| @starting-style { |
| #target { background-color: white; } |
| } |
| } |
| @container (width < 300px) { |
| @starting-style { |
| #target { background-color: red; } |
| } |
| } |
| </style> |
| <script> |
| promise_test(async t => { |
| await waitForAnimationFrames(2); |
| assert_equals(getComputedStyle(target).backgroundColor, "rgb(0, 255, 0)", |
| "No transition while display:none"); |
| container.style.width = "400px"; |
| target.style.display = "block"; |
| await waitForAnimationFrames(2); |
| assert_equals(getComputedStyle(target).backgroundColor, "rgb(128, 255, 128)", |
| "@starting-style based on the size query evaluation from the same frame"); |
| }, "Triggered transition from first style update based on up-to-date container query"); |
| </script> |
