.header nav a:hover{
    background-color: #3267d6;
}

.header nav a:focus{
    background-color: #3267d6;
}

.header-menu:hover{
    background-color: #3267d6;
}

.header-menu:focus{
    background-color: #3267d6;
}

#header-menu:hover ~ .header-nav{
    display: inherit;
}

#header-menu:focus ~ .header-nav{
    display: inherit;
}

#header-menu:target ~ .header-nav{
    display: inherit;
}

#header-menu:active ~ .header-nav{
    display: inherit;
}

.header-nav:hover{
    display: inherit;
}

.header-nav:target{
    display: inherit;
}

.header-nav:active{
    display: inherit;
}

.header-nav ul li .header-nav-button:hover img{
    -webkit-filter:  brightness(10) grayscale(1);
}

.header-nav ul li .header-nav-button:hover{
    background-color: #3181cd;
    color: #FFF;
}

.header-nav ul li:hover nav{
    display: inherit;
}