How to use custom css – http://help.wpresidence.net/article/how-to-add-custom-css/

.wg-drop.country-selector:not(.closed) ul {
display: block;
background-color: white;
max-height: 300px;
overflow-y: auto;
visibility: visible!important;
opacity: 1!important;
margin-left: 0px!important;
padding-top: 0px!important;
width: 169px!important;
}
.wg-drop.country-selector .wgcurrent a {
padding-right: 60px!important;
}