Rounded Triangle by css

index.html

<div class='triangle'></div>

style.css

/**
 * How to make 3-corner-rounded triangle in CSS (SO)
 * http://stackoverflow.com/q/14446677/1397351
 */
.triangle {
	position: relative;
	background-color: orange;
	text-align: left;
}
.triangle:before,
.triangle:after {
	content: '';
	position: absolute;
	background-color: inherit;
}
.triangle,
.triangle:before,
.triangle:after {
	width:  10em;
	height: 10em;
	border-top-right-radius: 30%;
}

.triangle {
	transform: rotate(-60deg) skewX(-30deg) scale(1,.866);
}
.triangle:before {
	transform: rotate(-135deg) skewX(-45deg) scale(1.414,.707) translate(0,-50%);
}
.triangle:after {
	transform: rotate(135deg) skewY(-45deg) scale(.707,1.414) translate(50%);
}



/* styles below for demonstration purposes only */
body { padding: 30%; }
.triangle:hover { background: rgba(0,0,255,.5) }
.triangle:hover:before { background: rgba(255,0,0,.5) }
.triangle:hover:after { background: rgba(255,255,0,.5) }