.parentsidebar {
    position: relative;
}

    .parentsidebar .left-submenu {
        display: none;
        position: absolute;
        top: 0;
        left: 100%;
        margin-left: 0.25rem;
        min-width: 200px;
        z-index: 9999;
    }

    .parentsidebar.show > .left-submenu {
        display: block;
    }

    .parentsidebar:hover > .left-submenu {
        display: block;
    }