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chromium/third_party/blink/web_tests/fast/borders/border-radius-wide-border-01.html 

<html> 
<head>
<style type="text/css"> 
#right-border, #bottom-border {
    background-color: red;
    width: 100px;
    height: 100px;
    border-radius: 10px;
}
#right-border {
border-right: 100px solid blue;
}
#bottom-border {
    margin-top: 10px;
    border-bottom: 100px solid blue;
}
</style> 
</head> 
<body>
  <div id="right-border"></div>
  <div id="bottom-border"></div>
</body> 
</html>