#site-menu .shared-menu-parent { position: relative; }
#site-menu .gallery-submenu {
    display: none;
    position: absolute;
    top: 0;
    left: 100%;
    min-width: min(200px, calc(100vw - 16px));
    max-width: calc(100vw - 16px);
    box-sizing: border-box;
    padding: 0 0 0 20px;
    margin: 0;
    background: #fff;
    box-shadow: 0 5px 12px rgba(0,0,0,.15);
    z-index: 9999;
}
#site-menu .gallery-submenu a { overflow-wrap: anywhere; }
#site-menu .shared-menu-parent:hover > .gallery-submenu,
#site-menu .shared-menu-parent:focus-within > .gallery-submenu,
#site-menu .shared-menu-parent.is-open > .gallery-submenu { display: block; }