body { padding-top: 70px; }
.nav_logo img{
	margin-left: 20%;
	width:80px;
	display: block;
	float:left;
}

nav{
	height: 100px;
}
.nav_btn {
    display: flex;
    position: absolute;
    right: 20vw;top: 0;
    height:100px;
    margin: 0;
}

.nav_btn li{
	padding: 0;
	height: 100%;
	display: inline-block;
}

.nav_btn li a{
	width: 100%;
	height: 100%;
	display: inline-block;
    position: relative;
    padding:0 20px;
    font-size: 18px;
    color: rgb(228, 228, 228);
    line-height:100px;
    /*transition: 0.2s all linear;*/
    cursor: pointer;
}

.nav_btn li a::before {
    content: "";
    position: absolute;
    top: -3px;
    left: 100%;
    width: 0;
    height: 100%;
    /*border-bottom: 3px solid rgb(83, 83, 83);*/
    /*transition: 0.2s all linear;*/
}

.nav_btn li a:hover::before {
    width: 100%;
    top: -3px;
    left: 0;
    transition-delay: 0.1s;
    border-bottom-color: rgb(83, 83, 83);
}

.nav_btn li a:hover ~ a::before {
    left: 0;
}

.nav_btn li>a{
	width: 100%;
	text-decoration: none;
	color: rgb(119, 119, 119);
}

.nav_btn li>a:hover{
	color: rgb(77, 77, 77);
}

.sec{
	transition: all 0.5s;
	
}
.sec img:hover{
	transform: scale(1.05);
}
.section{
	display: flex;
	justify-content: center; 
	margin-top:50px;
	text-align: center
}

.section>div{
	width:300px;
	height:300px;
	background:rgb(255,255,204); 
	border-radius:150px ; 
	margin:30px;
	color: black;
	padding: 80px 20px 0 20px;
	transition: all 0.3s;
}

.section>div:hover{
	transform: scale(1.05)
}

footer{
	background-color:rgb(37, 37, 37) ;
	display: flex; 
	justify-content: center;
	color: rgb(255, 255, 255);
	height: 130px;
	line-height: 70px;
	width: 100%;
	margin-top: -10px;
}
footer address{
	width: 50%;
	margin-top: 10px;
	margin-left: 40%;
	padding-top: 20px;
}
.show{
	
	border-bottom: 3px solid rgb(83, 83, 83)
}
.menu {
  width: 82px;
  padding-top: 1px;
  display: none;
}
.tab:hover + .menu-bar .menu, .menu:hover{
	display: block;
} 


/* 显示下拉菜单 */
.menu-item {
  width: 170px;
  background-color: white;
  border-bottom: 1px solid #ddd;
  border-right: 1px solid #ddd;
  border-left: 1px solid #ddd;
  cursor: pointer;
}
.menu-item:first-child {
  border-top: 1px solid #ddd;
}
.menu-item:hover {
  background-color: #ddd;
}
.menu-bar {
	position: absolute;
	top: 70px;
	left: 100px;
  	z-index: 100;   
}
.menu-bar ul {
  list-style-type:none;
}
.menu-bar li a {
  text-decoration: none;
  color: black;
  font-size: 12px;
  font-family: "宋体";
}