<!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-conditional-5/#animated-containers">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/css/css-transitions/support/helper.js"></script>
<body>
</body>
<style>
#container {
container-type: inline-size;
width: 100px;
}
#target {
transition-property: background-color;
transition-duration: 100s;
transition-timing-function: steps(2, start);
background-color: lime;
display: none;
}
@container (width > 300px) {
@starting-style {
#target { background-color: white; }
}
}
@container ((width > 200px) and (width < 300px)) {
#target {
display: block;
}
@starting-style {
#target { background-color: white; }
}
}
@container (width < 200px) {
@starting-style {
#target { background-color: red; }
}
}
</style>
<script>
function setup(test) {
let container = document.createElement("div");
container.id = "container";
document.body.appendChild(container);
let target = document.createElement("div");
target.id = "target";
container.appendChild(target);
test.add_cleanup(() => {
target.remove();
container.remove();
});
return [container, target];
}
promise_test(async t => {
let [container, target] = setup(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");
promise_test(async t => {
let [container, target] = setup(t);
await waitForAnimationFrames(2);
assert_equals(getComputedStyle(target).backgroundColor, "rgb(0, 255, 0)",
"No transition while display:none");
container.style.width = "250px";
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 the display change inside the up-to-date " +
"container query");
</script>
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