Пожалуйста, попробуйте этот код
body {
background: #ccc;
}
.circle {
margin: 25px 0;
width: 200px;
height: 200px;
border-radius: 50%;
border: 12px solid transparent;
background-size: 100% 100%, 100% 50%,100% 100%, 100% 50%;
background-repeat: no-repeat;
background-image: linear-gradient(white, white),
linear-gradient(360deg, green 100%, lightgrey 100%),
linear-gradient(360deg, red 100%, lightgrey 100%);
background-position: center center, left top, right top, left bottom, right bottom;
background-origin: content-box, border-box, border-box, border-box, border-box;
background-clip: content-box, border-box, border-box, border-box, border-box;
transform: rotate(90deg);
}
<div class="circle">
</div>
Скрипка: http://jsfiddle.net/66r7nj4x/