.header{
    /* 防抖动？ */
    /* list-style: none; */
    padding: 0;
    margin: 0;
    /* text-decoration: none; */
    box-sizing: border-box;
    font-family: 'poppins',sans-serif;
    width: 100%;
    height: 100vh;
    background-position: center;
    background-size: cover;
}
nav{
    width: 100%;
    padding: 20px 0;
    text-align: center; 
    transition: padding 1s;
    overflow-x: hidden;
    /* box-shadow: 2px 5px 15px rgb(0,0,0,.7); */
}
.logo{
    width: 300px;
    /* height: 40%; */
    margin: 100px 0;
    cursor: pointer;
    border-radius: 30%;
}

nav ul{
    background-color:#000;
    opacity: 0.85;
    width: 100%;
    /* height: auto; */
    /* margin-top: 10px; */
}
nav ul li{
    display: inline-block;
    list-style: none;
    margin: 20px 30px ;
    color:#fff;
}
nav.sticky ul li{
    padding: 10px;
    margin: 1px 5px ;
}

a{
    text-decoration: none;color: aliceblue;
}
/* nav.sticky a{
    color: #000;
} */
.na{
    color: #000;
    padding: 10px;
    background-color: #fff;
    border-radius: 10px;
    margin: 10px 15px ;
    transition: 0.5s;
}
nav.sticky{
    /* height: 60px; */
    position: fixed;
    top: 0;
    left: 0;
    padding: 5px 8%;
    background: #000;
    opacity: 0.85;
    align-items: center;
    display: flex;
    justify-content: space-between;
    transition: padding 1s;
    
}
nav.sticky ul{
    padding-right: 8%;
    width: auto;
    /* height: 60px; */
    padding-top: 0;
    margin: 0;
}
nav.sticky .logo{
    height: 50px;
    width: auto;
    margin:0;
}