Scale connected border with map zoom

src/world_map.rs

@@ -177,6 +177,7 @@ impl WorldMap {
 
         let painter = ui.painter_at(available);
         let stroke_w = (0.8 * self.zoom).min(2.0);
+        let connected_stroke_w = stroke_w + (0.5 * self.zoom).min(1.5);
         let south_pole_y = self.projection.project(0.0, -90.0, virtual_rect).y;
         let mut antarctica_fill = COLOR_UNAVAILABLE;
 
@@ -218,7 +219,7 @@ impl WorldMap {
                         &*self.projection,
                         virtual_rect,
                         COLOR_BORDER,
-                        stroke_w + 1.5,
+                        connected_stroke_w,
                     );
                 }
             }