Use CSS z-index to order layers

rendering/cases/vector-zindex/main.js

@@ -0,0 +1,50 @@
+import Map from '../../../src/ol/Map.js';
+import View from '../../../src/ol/View.js';
+import Feature from '../../../src/ol/Feature.js';
+import LineString from '../../../src/ol/geom/LineString.js';
+import VectorLayer from '../../../src/ol/layer/Vector.js';
+import VectorSource from '../../../src/ol/source/Vector.js';
+import Style from '../../../src/ol/style/Style.js';
+import Stroke from '../../../src/ol/style/Stroke.js';
+
+
+const vectorSourceRed = new VectorSource();
+const vectorSourceBlue = new VectorSource();
+let feature;
+
+feature = new Feature({
+  geometry: new LineString([[-60, 20], [45, 20]])
+});
+feature.setStyle(new Style({
+  stroke: new Stroke({color: '#f00', width: 10})
+}));
+vectorSourceRed.addFeature(feature);
+
+
+feature = new Feature({
+  geometry: new LineString([[0, -50], [0, 60]])
+});
+feature.setStyle(new Style({
+  stroke: new Stroke({color: '#00f', width: 16})
+}));
+vectorSourceBlue.addFeature(feature);
+
+new Map({
+  pixelRatio: 1,
+  layers: [
+    new VectorLayer({
+      zIndex: 1,
+      source: vectorSourceRed
+    }),
+    new VectorLayer({
+      source: vectorSourceBlue
+    })
+  ],
+  target: 'map',
+  view: new View({
+    center: [0, 0],
+    resolution: 1
+  })
+});
+
+render();