Fix opacity handling for tile and vector layers

src/ol/css.js

@@ -114,3 +114,11 @@ export const getFontParameters = function (fontSpec) {
   style.families = style.family.split(/,\s?/);
   return style;
 };
+
+/**
+ * @param {number} opacity Opacity (0..1).
+ * @return {string} CSS opacity.
+ */
+export function cssOpacity(opacity) {
+  return opacity === 1 ? '' : String(Math.round(opacity * 100) / 100);
+}