.header{
    width: 840px;
    height: 50px;
    margin: auto;
    padding-top: 40px;
    background-color:none;
    position: sticky;
    top:-15px ;
    z-index: 1;
    background-color:white;
}
#logo{
    width: 40px;
    float: left;
    position: relative;/*logo上移*/
    left: 30px; 
    bottom: 5px;
}
.clear{clear:both;}/*浮动清除*/
nav a{
    text-decoration:none;
    color: inherit;
    display: block;
    padding: 7px 0 3px 0;
    font-size: 15px;
    font-family: Calibri,Arial, Helvetica, sans-serif;
    /*font-family: Helvetica, Tahoma, Arial, "Microsoft YaHei", "Hiragino Sans GB", "WenQuanYi Micro Hei", sans-serif;*/
    font-weight: bold;
}
.dropdown li a{
    font-size: 14px;
    padding: 5px 0 ;
}/*下拉菜单字体大小*/

span{margin: 0;padding: 0;}
/*nav a span{
}下划线悬停效果 无*/
nav a:hover span{
    border-bottom: solid 1px rgba(69,138,57,1);

}/*下划线*/
nav ul{
    list-style: none;
    background-color: none;
    margin: 0;
    padding: 0;
}
nav li{
    width: 90px;
}/*btn width*/
.flex-nav{
    display: flex;
    justify-content: flex-end;
}/*导航水平*/
.dropdown li{
    width: 120px;
}/*dropdown width*/

.dropdown{
    display: none;
}

li:hover .dropdown{
    display: block;
    background-color:white;
    width: 140px;
    padding-left: 10px;
    margin-left: -10px;
}
.lan{
    position: fixed;
    margin: 0;
    padding: 0;
    top:15px;
    right:15px;
    text-decoration: none;
    color:#555;
    font-size: 14px;
    transition: 0.35s;
    font-family: Calibri,Arial, Helvetica, sans-serif;
}
.lan:hover{
    color: #458a39;
}

.preload {
	-webkit-transition: none !important;
	-moz-transition: none !important;
	-ms-transition: none !important;
	-o-transition: none !important;
	transition: none !important;
}