JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://openlayers.org/api/2.12/OpenLayers.js"></script>
<div id="map"></div>

CSS

#map {width: 370px; height: 420px;}

JavaScript

var lon = 15.43, lat = 47.07, zoom = 12;
var map = new OpenLayers.Map('map',{
    projection: "EPSG:3857",
    displayProjection: "EPSG:4326",
    layers: [
        new OpenLayers.Layer.WMS(
            "ogd graz",
                        "http://geodaten1.graz.at/ArcGIS_Graz/services/Extern/BASISKARTE_WMS/MapServer/WMSServer",
            {layers: '1,3'}, {numZoomLevels: 20}
        ),
        new OpenLayers.Layer.OSM()
    ],
    center: new OpenLayers.LonLat(lon, lat, zoom).transform("EPSG:4326", "EPSG:3857"),
    zoom: zoom
});
map.addControl(new OpenLayers.Control.LayerSwitcher());
map.addControl(new OpenLayers.Control.MousePosition());