<!DOCTYPE html>
<html>
<head>
<style>
#round1 {
border-radius: 50px/15px;
background: #73AD21;
padding: 20px;
width: 200px;
height: 150px;
}
#round2 {
border-radius: 15px/50px;
background: #73AD21;
padding: 20px;
width: 200px;
height: 150px;
}
#round3 {
border-radius: 50%;
background: #73AD21;
width: 200px;
height: 200px;
}
</style>
</head>
<body>
<div id="round1">Borde eliptico</div><br><br>
<div id="round2">Borde eliptico</div><br><br>
<div id="round3">Redondo</div>
</body>
</html>