<style>div { position:absolute; width:200px; height:200px; }</style>
<div style="background: radial-gradient(closest-side circle at 60px 80px, white, black 100px); top:10px; left:10px;"></div>
<div style="background: radial-gradient(closest-side circle at 140px 80px, white, black 100px); top:10px; left:220px;"></div>
<div style="background: radial-gradient(closest-side circle at 80px 60px, white, black 100px); top:220px; left:10px;"></div>
<div style="background: radial-gradient(closest-side circle at 80px 140px, white, black 100px); top:220px; left:220px;"></div>
<div style="background: -moz-radial-gradient(60px 80px 90deg, closest-corner, white, black 80px); top:430px; left:10px;"></div>
<div style="background: -moz-radial-gradient(140px 80px 90deg, closest-corner, white, black 80px); top:430px; left:220px;"></div>
<div style="background: -moz-radial-gradient(80px 60px 90deg, ellipse closest-corner, white, black 60px); top:640px; left:10px;"></div>
<div style="background: -moz-radial-gradient(80px 140px 90deg, ellipse closest-corner, white, black 60px); top:640px; left:220px;"></div>