If you’d like to modify the menu item button colour, then you can use the following custom css:
/* Standard State */
nav ul.menu > li.menu-item.sf-menu-item-btn > a > span.menu-item-text {
border-color: #fff;
background-color: #fff;
color: #222;
}
/* Hover State */
nav ul.menu > li.menu-item.sf-menu-item-btn:hover > a > span.menu-item-text {border-color: #ff9900;
background-color: #ff9900;
color: #fff;
}
