You can make use of this CSS to manipulate the color of the map:
CSS
.open-user-map .box-wrap .map-wrap .leaflet-map {
background-color: red; /* insert your color here */
}
.open-user-map .box-wrap .map-wrap .leaflet-map .leaflet-tile-pane img.leaflet-tile {
opacity: 0.5 !important;
}This will set a background color for the map and make the overlaying map tiles a little transparent.