<header>
        <div class="logo">
            <a href="index.html"><img src="img/logo.png" alt="萬佳鄉"></a>
        </div>
            <ul class="menu">
                <li><a href="#">關於萬佳鄉</a></li >
                <li><a href="#">美味餐點</a></li> 
                <li><a href="#">加盟專區</a></li> 
                <li><a href="#">優質門市</a></li> 
                <li><a href="#">影音專區</a></li> 
                <li><a href="#">聯絡我們</a></li> 
            </ul>
    </header>

header{
    width: 100%;
    display:flex;
    background:url(../img/menu_bg.png);
    justify-content:space-around;
    align-items: center;
    position:fixed;
    .menu{
        display:flex;
        justify-content: space-around;
        width: 70%;
        a{
            color:#e9e9e9;
            text-decoration:none;
        }
    }
}

想要固定表頭在上面，但是往下寫 之後就被表頭蓋住了，這樣要怎麼辦