*{
	box-sizing: border-box;
	word-break:break-all;
}
body
{
	margin: 0;
	padding: 0;
	overflow-x:hidden ;
	font-size: 100%;
}
.header{
	height:100px;
	position: relative;
	background-color:#f6f6f6 ;
	padding: 10px 50px;
}
.header img{
	height: 80px;
	width: 280px;
}
.welcome{
	display: block;
	position: absolute;
	top: 0;
	left: 800px;
	font-size: 2.5em;
	font-family: "楷体";
	line-height: 100px;
	color: rgba(255,103,0,1.00);
	margin: 0;
	width: 450px;
}
nav{
	position: sticky;
	display:flex;
	top: 0;
	width: 100%;
	height: 50px;
	z-index: 1;
	background-color: rgba(239,175,0,1.00);
	justify-content: space-around;
}
nav a{
	display: block;
	text-align: center;
	height: 100%;
	width: 20%;
	line-height: 50px;
	font-size: 1.5em;
	text-decoration: none;
	color: white;
}
nav a:hover:not(.active){
	background-color: rgba(255,196,35,1.00);
}
.active{
	background-color: #4caf50
}
.tipstest{
	position: relative;
	color: #DDDDDD;
	text-align: center;
	width:200px;
	background-color: #EFEFEF;
	float: right;
}
.tipstest:hover .tips{
	display: block;
	z-index: 2;
}
.tips{
	position: absolute;
	display: none;
	background-color: black;
	color: white;
	bottom: 100%;
	left:50%;
	margin-left: -60px;
	border-radius: 10px;
	margin-bottom: 5px;
	padding: 5px;
	width:120px;
}
.tips::after{
	content: "";
	position: absolute;
	border-style:solid;
	border-width: 8px;
	width:0px;
	border-color: black transparent transparent;
	top:100%;
	left:50%;
	margin-left: -8px;
}
.grid{
	display: grid;
	grid-template-columns: 20% 40% 40%;
	grid-template-rows: 100px 200px;
	
}