tor-browser

The Tor Browser
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last-successful-pseudo-element-fallbacks.html (2252B)

      1 <!DOCTYPE html>
      2 
      3 <title>CSS Anchor Positioning: changing position-try-fallbacks invalidates last successful position fallback on pseudo-elements</title>
      4 <link rel="author" title="Kiet Ho" href="mailto:kiet.ho@apple.com">
      5 
      6 <link rel="help" href="https://drafts.csswg.org/css-anchor-position/#last-successful-position-fallback">
      7 
      8 <script src="/resources/testharness.js"></script>
      9 <script src="/resources/testharnessreport.js"></script>
     10 <script src="support/test-common.js"></script>
     11 
     12 <style>
     13  #container {
     14    position: relative;
     15    width: 400px;
     16    height: 400px;
     17    background: teal;
     18  }
     19  #anchor {
     20    position: relative;
     21    top: 100px;
     22    left: 100px;
     23    width: 100px;
     24    height: 100px;
     25    background: red;
     26    anchor-name: --a;
     27  }
     28  #anchored::before {
     29    position-anchor: --a;
     30    bottom: anchor(top);
     31    left: anchor(left);
     32    position-try-fallbacks: flip-block;
     33    position: absolute;
     34    width: 100px;
     35    height: 200px;
     36    background: lime;
     37    content: "";
     38  }
     39  /*
     40    Hack to change position-try-fallbacks of the pseudo-element,
     41    since there's no easy way to change it in JavaScript.
     42  */
     43  #anchored.new-fallback::before {
     44    position-try-fallbacks: flip-block, --foo;
     45  }
     46 </style>
     47 
     48 <div id="container">
     49  <div id="anchor"></div>
     50  <div id="anchored"></div>
     51 </div>
     52 <script>
     53  promise_test(async () => {
     54    await waitUntilNextAnimationFrame();
     55    await waitUntilNextAnimationFrame();
     56    const anchoredStyle = getComputedStyle(anchored, "::before");
     57    assert_equals(anchoredStyle.top, "200px");
     58  }, "Starts rendering with flip-block");
     59 
     60  promise_test(async () => {
     61    anchor.style.top = "150px";
     62    await waitUntilNextAnimationFrame();
     63    await waitUntilNextAnimationFrame();
     64    const anchoredStyle = getComputedStyle(anchored, "::before");
     65    assert_equals(anchoredStyle.top, "250px");
     66  }, "No successful position, keep flip-block");
     67 
     68  promise_test(async () => {
     69    anchored.classList.add("new-fallback");
     70    await waitUntilNextAnimationFrame();
     71    await waitUntilNextAnimationFrame();
     72    const anchoredStyle = getComputedStyle(anchored, "::before");
     73    assert_equals(anchoredStyle.top, "-50px");
     74  }, "No successful position, last successful invalidated by position-try-fallbacks change");
     75 </script>