#mainnav {
    background-color: #333 !important;
}

#mainnav > ul > li {
    list-style-type: none;
    display: inline-block;
    height: 90px; 
}

#mainnav > ul > li > a {
    display: block; width: 100%; height: 100%;
    color: whitesmoke; text-decoration: none;
    line-height: 86px; padding: 0 8px;
    font-family: Verdana, Geneva, Tahoma, sans-serif; font-size: .9em;
    position: relative;
}

#mainnav > ul > li > a:hover {
    color: #777
}

#mainnav > ul > li:hover > a::after {
    content: "\25b2"; color: #fff;
    position: absolute; left: 50%; bottom: -35px;
    transform: translateX(-50%) scale(1.5);
}

#mainnav nav.submenu {
    position: absolute; left: 0px; top: 90px;
    width: 750px; height: 380px;
    z-index: 2;
    display: none;
    box-shadow: 2px 2px 5px #222;
}

#mainnav > ul > li:hover .submenu {
    display: flex;
}

#mainnav nav.submenu > ul {
    list-style-type: none;
    flex: 1 0 50%;
    background-color: white;
}

#mainnav nav.submenu > ul > li > a {
    display: block; width: 100%; height: 35px;
    font-family: Verdana, Geneva, Tahoma, sans-serif;
    text-decoration: none;
    color: black;
    line-height: 30px; font-size: .9em;
    text-indent: 16px;
    position: relative;
}

#mainnav nav.submenu > ul > li > a.special {
    color: #A00;
}

#mainnav nav.submenu > ul > li > a:hover {
    text-decoration: underline;
}

#mainnav nav.submenu > ul > li > a::after {
    content: "\25b6";
    position: absolute; right: 8px; top: 0px;
}

#mainnav nav.submenu > ul > li > a.nosub::after {
    content: "";
    position: absolute; right: 8px; top: 0px;
}

.submenu .submenu-promo {
    background-color: green;
    flex: 1 0 50%;
    background-image: url(../images/boots.jpg);
    background-size: cover;
    background-position: bottom;
    position: relative;
}

.submenu .submenu-promo > span {
    display: block; width: 10ch;
    text-decoration: none;
    text-transform: uppercase;
    font-weight: bold;
    font-size: 1.7em;
    color: white; font-family: Verdana, Geneva, Tahoma, sans-serif;
    position: absolute; left: 20px; bottom: 20px;
}

.submenu .submenu-promo span span {
    text-transform: capitalize;
    font-weight: normal;
    font-size: .6em; line-height: 4;
    text-decoration: underline;
}

nav.submenu > ul > li:hover {
    background-color: lightgray;
}

/* submenu2 isn't a child, it's a sibling of submenu; it's adjacent to the anchor */

ul.submenu2 {
    list-style-type: none;
    position: absolute; left: 375px; top: 0px;
    z-index: 4;
    background-color: lightgray;
    width: 375px; height: 80%;
    display: none;
}

#mainnav nav.submenu > ul > li:hover > a + .submenu2 {
    display: block;
}

ul.submenu2 a {
    text-decoration: none;
    color: black;
    font-family: Verdana, Geneva, Tahoma, sans-serif;
    display: block; height: 30px; line-height: 28px;
    text-indent: 18px; font-size: .9em;
}

ul.submenu2 a:hover {
    text-decoration: underline;
}