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Test Info:
<!DOCTYPE html>
<html class="reftest-wait">
<title>
Removing !important rule during delay phase of animation creates
a stack context for correct style
</title>
<style>
span {
height: 100px;
width: 100px;
position: fixed;
background: green;
top: 50px;
}
@keyframes Opacity0 {
from, to { opacity: 0 }
}
#test {
width: 100px; height: 100px;
background: blue;
animation: Opacity0 100s 100s;
}
</style>
<span></span>
<div id="test"></div>
<script>
window.addEventListener("load", () => {
var target = document.getElementById("test");
target.style.setProperty("opacity", "0.1", "important");
requestAnimationFrame(() => {
// Now the target opacity style should be 0.1 because of !important rule.
// Apply 100% opacity without important directive.
target.style.setProperty("opacity", "1", "");
requestAnimationFrame(() => {
// The CSS animation is no longer overridden but it's still in delay
// phase, so we should create a stacking context for 100% opacity style.
document.documentElement.classList.remove("reftest-wait");
});
});
});
</script>