header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    padding: 5px 0;
    z-index: 1;
}

header.top {
    background-color: #0009;
}

header:not(.top) {
    background-color: #121212;
}

header nav .nav a {
    text-decoration: none;
    color: var(--white);
    transition: color 0.3s ease;
    text-transform: uppercase;
}

header nav .nav a:hover {
    color: var(--orange);
}

/* Mobile & Tablet */
@media (max-width: 1279.999px) {
    header .logo img {
        width: 60px;
        height: 60px;
    }

    header .xE {
        float: right;
    }

    header nav {
        text-align: center;
        overflow: hidden;
        height: 0;
        transition: height .5s;
    }

    body.nav header nav {
        overflow-y: auto; /* скрол по вертикала */
        height: calc(100vh - 84px);
    }

    header nav > a.button:first-child {
        margin: 30px 0 10px 0;
    }

    header nav .nav div {
        margin: 20px 0;
    }
}

/* Desktop */
@media (min-width: 1280px) {
    header .logo img {
        transition: width .5s, height .5s;
        width: 100px;
        height: 100px;
    }

    header:not(.top) .logo img {
        width: 60px;
        height: 60px;
    }

    header .xE {
        display: none;
    }

    header nav {
        float: right;
        width: calc(100% - 150px);

        transition: padding .5s;
    }

    header:not(.top) nav {
        padding: 7px 0;
    }

    header.top nav {
        padding: 28px 0;
    }

    header nav > a.button:first-child { /* INFO: Contact Us */
        float: right;
    }

    header nav .nav {
        margin-right: 270px;
    }

    header nav .nav div {
        display: inline-block;
    }

    header nav .nav a {
        display: inline-block;
        padding: 10px;
    }
}