chromium/third_party/blink/web_tests/external/wpt/css/css-animations/animation-delay-001-manual.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Animations Test: animation-delay - negative value</title>
<link rel="author" title="Nokia Inc." href="http://www.nokia.com">
<link rel="author" title="Intel" href="http://www.intel.com">
<link rel="reviewer" title="Zhiqiang Zhang" href="mailto:[email protected]"> <!-- 2015-03-18 -->
<link rel="help" href="https://drafts.csswg.org/css-animations-1/#animation-delay">
<link rel="help" href="https://drafts.csswg.org/css-animations-1/#animation-name">
<link rel="help" href="https://drafts.csswg.org/css-animations-1/#animation-duration">
<link rel="help" href="https://drafts.csswg.org/css-animations-1/#animation-timing-function">
<meta name="flags" content="animated">
<meta name="assert" content="When animation-delay is set to a negative time offset,
                             animation will execute as soon as it is applied
                             but act as if the animation had started the specified
                             time in the past.">
<style>
  div {
    animation-timing-function: linear;

    height: 100px;
    width: 100px;
    position: relative;
  }

  #test-negative-delay {
    animation-name: test-negative-delay;
    animation-duration: 10s;
    animation-delay: -5s;

    background-color: blue;
  }

  #ref-no-delay {
    animation-name: ref-no-delay;
    animation-duration: 5s;

    background-color: yellow;
  }

  @keyframes test-negative-delay {
    from {
      left: 150px;
    }
    to {
      left: 0px;
    }
  }

  @keyframes ref-no-delay {
    from {
      left: 75px;
    }
    to {
      left: 0px;
    }
  }
</style>
<body>
  <p>
    Test passes if there are a filled blue square with 'Filler Text'
    and a filled yellow square with 'Filler Text', and if the two squares
    start moving together from right to left as soon as the page loads.
  </p>
  <div id="test-negative-delay">Filler Text</div>
  <div id="ref-no-delay">Filler Text</div>
</body>