<!DOCTYPE html>
<title>CSS Transitions Test: Cascading @starting-style</title>
<link rel="help" href="https://drafts.csswg.org/css-transitions-2/#defining-before-change-style-the-starting-style-rule">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/css/css-transitions/support/helper.js"></script>
<style>
  .color-transition {
    transition: color 100s steps(2, start);
  }

  @starting-style {
    #t1 { color: red; }
  }
  #t1 { color: green; }

  @starting-style {
    div#t2 { color: lime; }
  }
  #t2 { color: green; }

  #t3 { color: green; }
  @starting-style {
    #t3 { color: red; }
  }
  #t3 > div { color: green; }

  #t4 { color: green; }
  #t4[hidden] { color: red; }
  #t4 > div { color: lime; }
  @starting-style {
    #t4 > div { color: inherit; }
  }

  #t5 { color: green; }
  @starting-style {
    #t5 { color: black; }
  }
  #t5 > div { color: lime; }
  @starting-style {
    #t5 > div { color: inherit; }
  }
</style>
<div id="t1" hidden class="color-transition"></div>
<div id="t2" hidden class="color-transition"></div>
<div id="t3" hidden>
  <div class="color-transition"></div>
</div>
<div id="t4" hidden>
  <div class="color-transition"></div>
</div>
<div id="t5" hidden class="color-transition">
  <div class="color-transition"></div>
</div>
<script>
  promise_test(async t => {
    await waitForAnimationFrames(2);
    t1.removeAttribute("hidden");
    await waitForAnimationFrames(2);
    assert_equals(getComputedStyle(t1).color, "rgb(0, 128, 0)",
                  "No transition of color");
  }, "Overridden @starting-style - order of appearance");

  promise_test(async t => {
    t2.removeAttribute("hidden");
    await waitForAnimationFrames(2);
    assert_equals(getComputedStyle(t2).color, "rgb(0, 192, 0)",
                  "Transition of color");
  }, "@starting-style with higher specificity");

  promise_test(async t => {
    t3.removeAttribute("hidden");
    await waitForAnimationFrames(2);
    assert_equals(getComputedStyle(t3.firstElementChild).color, "rgb(0, 128, 0)",
                  "No transition of color");
  }, "Starting style does not inherit from parent starting style");

  promise_test(async t => {
    assert_equals(getComputedStyle(t4).color, "rgb(255, 0, 0)",
                  "Parent transition started");
    t4.removeAttribute("hidden");
    await waitForAnimationFrames(2);
    assert_equals(getComputedStyle(t4).color, "rgb(0, 128, 0)",
                  "Parent changed to green");
    assert_equals(getComputedStyle(t4.firstElementChild).color, "rgb(0, 192, 0)",
                  "Transition started from parent's after-change style color");
  }, "Starting style inheriting from parent's after-change style");

  promise_test(async t => {
    t5.removeAttribute("hidden");
    await waitForAnimationFrames(2);
    assert_equals(getComputedStyle(t5).color, "rgb(0, 64, 0)",
                  "Parent transition started");
    assert_equals(getComputedStyle(t5.firstElementChild).color, "rgb(0, 192, 0)",
                  "Transition started from parent's after-change style color");
  }, "Starting style inheriting from parent's after-change style while parent transitioning");
</script>
