Create centered container with radial gradient background
HTML
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<div class="container"></div>
<style>
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
body {
height: 100svh;
}
.container {
width: min(500px, 100vw);
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
aspect-ratio: 1/1;
background-repeat: no-repeat;
background-image: radial-gradient(ellipse 100% 94.33% at 50% 0%, transparent 40%, red 0 42%, transparent 0);
background-size: 30.5% 30.5%;
background-position: 54.1% 100.75%;
}
</style>
</body>
</html>