How to change the style of grid border?

Hi everyone. Can anyone help me to change the style of grid border/edges black and white? The example of the border is attached.

Together I attached example of the script

  latlim = [0 40];
    lonlim = [85 139];
    coast = shaperead('landareas.shp','UseGeoCoords',true);
    coast.Geometry
    worldmap(latlim,lonlim);
    geoshow(coast,'FaceAlpha', 0.3, 'FaceColor','black');