<div class='octagon'>
	<div class='inner'>octagon</div>
</div>

$dim: 65vmin;

div {
	width: $dim; height: $dim;
	//box-shadow: 0 0 0 1px;
}

.octagon { overflow: hidden; }

.inner {
	transform: rotate(45deg);
	background: #ee8c25;
}