Można pokombinować z wysokością/szerokością, zerować border dla części, które są niepotrzebne i zaokrąglać właściwościami (border-top-right-radius, border-bottom-left-radius itd) 75% trzeba chyba złożyć z 2 kawałków.
<!DOCTYPE html>
<html>
<head>
<meta charset='utf-8'>
<meta http-equiv='X-UA-Compatible' content='IE=edge'>
<title>Circle</title>
<meta name='viewport' content='width=device-width, initial-scale=1'>
<style>
*{
box-sizing: border-box;
}
div {
background-color: white;
border: 3px solid black;
margin-top: 20px;
}
.percent-25 {
border-top-right-radius: 100px;
border-bottom: 0;
border-left: 0;
margin-left: 108px;
height: 100px;
width: 100px;
}
.percent-50 {
border-top-right-radius: 100px;
border-bottom-right-radius: 100px;
border-left: 0;
height: 200px;
margin-left: 108px;
width: 100px;
}
.percent-75 {
border: none;
position: relative;
margin-bottom: 260px;
}
.percent-75-a {
border-top-right-radius: 100px;
border-bottom-right-radius: 100px;
border-left: 0;
height: 200px;
left: 100px;
position: absolute;
top: 0;
width: 100px;
}
.percent-75-b {
border-bottom-left-radius: 100px;
border-top: 0;
border-right: 0;
height: 100px;
left: 0px;
position: absolute;
top: 100px;
width: 100px;
}
.percent-100 {
border-radius: 50%;
height: 200px;
width: 200px;
}
</style>
</head>
<body>
<div class='percent-25'></div>
<div class='percent-50'></div>
<div class='percent-75'>
<div class='percent-75-a'></div>
<div class='percent-75-b'></div>
</div>
<div class='percent-100'></div>
</body>
</html>
Mocno kombinowane, ale efekt powinien być taki: