overlays below traces

website/src/lib/components/Map.svelte

@@ -100,6 +100,17 @@
 
 		newMap.on('style.load', toggleTerrain);
 		newMap.on('pitch', toggleTerrain);
+
+		newMap.on('style.load', () => {
+			// add dummy layer to place the overlay layers below
+			newMap.addLayer({
+				id: 'overlays',
+				type: 'background',
+				paint: {
+					'background-color': 'rgba(0, 0, 0, 0)'
+				}
+			});
+		});
 	});
 
 	$: if ($map) {

website/src/lib/components/layer-control/LayerControl.svelte

@@ -69,7 +69,8 @@
 					if (!$map.getSource(id)) {
 						$map.addSource(id, overlays[id]);
 					}
-					$map.addLayer({
+					$map.addLayer(
+						{
 							id,
 							type: overlays[id].type === 'raster' ? 'raster' : 'line',
 							source: id,
@@ -80,7 +81,9 @@
 										: { 'line-opacity': opacities[id] }
 									: {})
 							}
-					});
+						},
+						'overlays'
+					);
 				} catch (e) {
 					// No reliable way to check if the map is ready to add sources and layers
 				}