repeating-radial-1c.html
<div style="background: repeating-radial-gradient(200px 200px at center, black 100px, black 150px, white 150px, white 200px); width: 400px; height: 400px;"></div>
<div style="background: repeating-radial-gradient(200px 200px at center, black 100px, black 150px, white 150px, white 200px); width: 400px; height: 400px;"></div>