If you want to place both columns one under another on mobile you need to set its width to 12 columns 1/1 in responsive settings. http://prntscr.com/iubpqs
Try to add the following code snippet to the Custom CSS area in Theme Settings to change menu style.
body .widget_product_categories {
background-color: #F7F7F7;
}
body .widget_product_categories .basel-cats-toggle {
top: 11px;
}
body .widget_product_categories .widget-title {
padding: 20px;
background-color: #E1008B;
margin-bottom: 0;
}
body .widget_product_categories .cat-item {
margin-bottom: 0;
}
body .widget_product_categories .cat-item .children {
margin-top: 0;
}
body .widget_product_categories .cat-item .children .cat-item a {
padding-left: 25px;
}
body .widget_product_categories .cat-item:before {
display: none;
}
body .widget_product_categories .cat-item > a {
display: block;
padding: 15px;
}
body .widget_product_categories .cat-item > a:hover,
body .widget_product_categories .current-cat > a {
background-color: #E1008B;
color: white;
}
Regards
.
