*{margin:0px;padding:0px;font-family:arial;}
header{width:100%;height:200px;background:transparent;display:flex;margin-top:20px;}
header h1{text-transform:uppercase;margin-bottom:20px;}
header ul li{list-style-type:none;margin:0px 20px;display:inline-block;position:relative;}
header ul li a{text-decoration:none;text-transform:uppercase;color:#000;}
header ul li::after{
	content:'';
	height:3px;
	width:0px;
	background:#009688;
	position:absolute;
	left:0px;
	bottom:-10px;
	transition:0.5s;
}
header ul li:hover:after{
	width:100%;
	
}