nav {
	position: fixed;
	width: 100%;
	top: 0;
	padding: 16px;
	z-index: 100;
  }
  nav .up {
	font: bold 14px/1 sans-serif;
	color: white;
	width: 92px;
	padding: 8px;
	background-color: rgba(230, 26, 60, 0.8);
	float: left;
	cursor: pointer;
  }
  nav .up:hover {
	background-color: rgba(184, 20, 48, 0.8);
  }
  
  .feature {
	position: relative;
	width: calc(100% - 0 * 2 * 1px);
	height: calc(100% - 0 * 2 * 1px);
	margin: 0px;
	overflow: hidden;
  }
  
  .node {
	position: absolute;
	background: transparent url("") no-repeat 50%/cover;
	overflow: hidden;
	opacity: 0.8;
	transition: opacity .8s;
	cursor: pointer;
  }
  .node .label {
	display: inline;
	font-family: sans-serif;
	color: rgba(255, 255, 255, 0.6);
	position: absolute;
	padding: 0;
	margin: 0;
	top: 50%;
	left: 50%;
	-webkit-transform: translateX(-50%) translateY(-50%);
			transform: translateX(-50%) translateY(-50%);
	transition: color .4s, opacity .8s, -webkit-filter .8s;
	transition: color .4s, opacity .8s, filter .8s;
	transition: color .4s, opacity .8s, filter .8s, -webkit-filter .8s;
  }
  .node.hide {
	opacity: 0;
	pointer-events: none;
  }
  .node.hide .label {
	-webkit-filter: blur(10px);
			filter: blur(10px);
  }
  .node:hover .label {
	color: white;
  }
  .node.level-0 {
	z-index: 4;
	font-size: 15vmin;
	display: none;
  }
  .node.level-1 {
	z-index: 3;
	font-size: 10vmin;
  }
  .node.level-2 {
	z-index: 2;
	font-size: 5vmin;
  }
  .node.level-3 {
	z-index: 1;
	font-size: 2.5vmin;
  }