Source: src/ol/style.jsdoc

/**
 * Feature styles.
 *
 * If no style is defined, the following default style is used:
 * ```js
 *  var fill = new ol.style.Fill({
 *    color: 'rgba(255,255,255,0.4)'
 *  });
 *  var stroke = new ol.style.Stroke({
 *    color: '#3399CC',
 *    width: 1.25
 *  });
 *  var styles = [
 *    new ol.style.Style({
 *      image: new ol.style.Circle({
 *        fill: fill,
 *        stroke: stroke,
 *        radius: 5
 *      }),
 *      fill: fill,
 *      stroke: stroke
 *    })
 *  ];
 * ```
 *
 * A separate editing style has the following defaults:
 * ```js
 *  var white = [255, 255, 255, 1];
 *  var blue = [0, 153, 255, 1];
 *  var width = 3;
 *  styles[ol.geom.GeometryType.POLYGON] = [
 *    new ol.style.Style({
 *      fill: new ol.style.Fill({
 *        color: [255, 255, 255, 0.5]
 *      })
 *    })
 *  ];
 *  styles[ol.geom.GeometryType.MULTI_POLYGON] =
 *      styles[ol.geom.GeometryType.POLYGON];
 *  styles[ol.geom.GeometryType.LINE_STRING] = [
 *    new ol.style.Style({
 *      stroke: new ol.style.Stroke({
 *        color: white,
 *        width: width + 2
 *      })
 *    }),
 *    new ol.style.Style({
 *      stroke: new ol.style.Stroke({
 *        color: blue,
 *        width: width
 *      })
 *    })
 *  ];
 *  styles[ol.geom.GeometryType.MULTI_LINE_STRING] =
 *      styles[ol.geom.GeometryType.LINE_STRING];
 *  styles[ol.geom.GeometryType.POINT] = [
 *    new ol.style.Style({
 *      image: new ol.style.Circle({
 *        radius: width * 2,
 *        fill: new ol.style.Fill({
 *          color: blue
 *        }),
 *        stroke: new ol.style.Stroke({
 *          color: white,
 *          width: width / 2
 *        })
 *      }),
 *      zIndex: Infinity
 *    })
 *  ];
 *  styles[ol.geom.GeometryType.MULTI_POINT] =
 *      styles[ol.geom.GeometryType.POINT];
 *  styles[ol.geom.GeometryType.GEOMETRY_COLLECTION] =
 *      styles[ol.geom.GeometryType.POLYGON].concat(
 *          styles[ol.geom.GeometryType.POINT]
 *      );
 *```
 *
 * @namespace ol.style
 */