border-radius-background-constrained.html

<!doctype html>
<style>
p {
    width: 100px;
    height: 100px;
    background-color: cyan;
    border: 10px double red;
    border-radius: 400px 0px 0px 400px / 20px 0px 0px 600px;
}
</style>
<p></p>

chromium/third_party/blink/web_tests/fast/borders/border-radius-background-constrained.html