header {
    display: var(--display-navigation);
    font-size: 1.3em;
    height: var(--size-header-height);
    justify-content: space-between;
    left: 50%;
    margin: 0;
    max-width: var(--size-max-width);
    position: fixed;
    top: 0;
    transform: translateX(-50%);
    transition: background-color var(--time-sky-transition);
    width: 100%;
    z-index: var(--z-index-navigation);  

    font-weight: 400;
}

header h1 {
    align-items: center;
    display: flex;
    font-size: 1.5em;
    font-weight: inherit;
    justify-content: center;
    margin: 0 10px;
}