<!DOCTYPE html>
<title>CSS Transitions Test: Basic tests for @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>
<div id="target" class="trans"></div>
<style>
#target {
transition-property: background-color, color;
transition-duration: 100s;
transition-timing-function: steps(2, start);
color: green;
background-color: white;
}
@starting-style {
#target {
background-color: black;
}
}
#target.red {
background-color: red;
}
</style>
<script>
promise_test(async t => {
await waitForAnimationFrames(2);
assert_equals(getComputedStyle(target).color, "rgb(0, 128, 0)",
"No transition of color");
assert_equals(getComputedStyle(target).backgroundColor, "rgb(128, 128, 128)",
"Background transition from @starting-style value black to white");
}, "Triggered transition from first style update");
promise_test(async t => {
target.style.display = "none";
target.className = "red";
assert_equals(getComputedStyle(target).backgroundColor, "rgb(255, 0, 0)",
"Overridden with red. No transition while display:none");
target.className = "";
assert_equals(getComputedStyle(target).backgroundColor, "rgb(255, 255, 255)",
"Removing class while display:none. Still no transition");
await waitForAnimationFrames(2);
target.style.display = "block";
await waitForAnimationFrames(2);
assert_equals(getComputedStyle(target).backgroundColor, "rgb(128, 128, 128)",
"Background transition from @starting-style value black to white");
}, "Triggered transition from display:none to display:block");
promise_test(async t => {
let removed = target;
removed.remove();
await waitForAnimationFrames(2);
document.body.appendChild(removed);
await waitForAnimationFrames(2);
assert_equals(getComputedStyle(target).backgroundColor, "rgb(128, 128, 128)",
"Background transition from @starting-style value black to white");
}, "Triggered transition on DOM insertion");
</script>
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