header {
    position: fixed;
    background-color: var(--lemon-white);
    z-index: 11;
    margin: 0;
    padding: 0;
    border-bottom: 1px solid var(--lemon-background-dark);
    width: 100%;
    font-size: 1rem;
    display: flex;
    justify-content: center;
}

    header a {
        text-decoration: none;
    }

    header h1 {
        margin: 0;
        padding: 1em 0;
        font-size: 1em;
    }