.header{
    position: fixed;
    height: 100px;
    width: 100%;
    background-color: white;
    z-index: 2;
    border-bottom: 1px solid #c9c9c9;
}
.logo{
    float: left;
}
.logo-img{
    height: 60px;
    position: absolute;
    left: 20px;
    top: 20px;
}
.menu{
    position: relative;
    right: 10%;
    float: right;
    height: 100%;
}
.tab{
    line-height: 100px;
    color: black;
    float: left;
    padding: 0 25px;
}
.tab span{
    font-size: 15px;
}
.tab:hover {
    cursor: pointer;
}
.sliding{
    margin-left: 30px;
    width: 0px;
    height: 5px;
    background-color: #0b5ceb;
    position: absolute;
    bottom: 0;
    transition: all 0.5s;
}
.tip{
    display: none;
    position: fixed;
    right: 5%;
    top: 20px;
    width: 200px;
    height: 100px;
    background-color: white;
    line-height: 100px;
    text-align: center;
    font-size: 14px;
    border: 1px solid #c9c9c9 ;
    border-radius:15px;
    box-shadow: 2px 2px 2px 1px rgba(0, 0, 0, 0.2);
}
.tip h4{
    line-height: 50px;
}
.tip p{
    line-height: 20px;
}

@media only screen and (max-width: 600px) {
 
    .header{
        position: fixed;
        height: 80px;
        width: 100%;
        max-width: 600px;
        background-color: white;
        z-index: 2;
        border-bottom: 1px solid #c9c9c9;
    }

    .logo-img{
        height: 40px;
        position: absolute;
        left: 20px;
        top: 20px;
    }

    .menu{
        position: relative;
        right: 80px;
        float: right;
        height: 100%;
    }

    .tab{
        line-height: 100px;
        color: black;
        float: left;
        padding: 0 5px;
    }
 
}