header {
    width: 100%;
    border-bottom: 1px solid #ccc;
    .app-header {
        width: 1200px;
        margin: 0 auto;
        display: flex;
        justify-content: space-between;
        height: 80px;
        line-height: 80px;

        .app-header-left {
            display: flex;
            align-items: center;
        }
        .app-header-right {
            font-size: 16px;
            ul {
                display: flex;
            }
        }
    }
}