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chromium/third_party/blink/web_tests/fast/backgrounds/mask-box-image-zoomed.html 

<!DOCTYPE html>
<style>
body {
    zoom: 2;
    margin: 0;
}
div {
    -webkit-mask-box-image: -webkit-linear-gradient(left,
        transparent, transparent 10px, black 10px,
        black 90px, transparent 90px, transparent);
    background: linear-gradient(0deg, green, green);
    width: 100px;
    height: 100px;
}
</style>
<div></div>