@media only screen and (max-width: 640px) { 
    #widget-override .simple-store .main-store-content .simple-store-content .simple-store-landing .top-category {
        width: 100%;
        margin:0;
        padding:0;
        margin-bottom:5px;
        float:none;        
    }
    
    #widget-override .simple-store .store-top-navigation ul li {
        float: none;
    }
}