/**
 * HTML5 / CSS3 Circle with Partial Border
 * http://stackoverflow.com/q/13059190/1397351
 */
* { margin: 0; padding: 0; }
.circle {
	position: relative;
	margin: 7em auto;
	width: 16em; height: 16em;
	border-radius: 50%;
	background: lightblue;
}
.arc {
	overflow: hidden;
	position: absolute;
	top: -1em; right: 50%; bottom: 50%; left: -1em;
	transform-origin: 100% 100%;
	transform: rotate(45deg) skewX(30deg);
}
.arc:before {
	box-sizing: border-box;
	display: block;
	border: solid 1em navy;
	width: 200%; height: 200%;
	border-radius: 50%;
	transform: skewX(-30deg);
	content: '';
}