function initMap() {
  var mycompany = {
    lat: 44.348534,
    lng: -79.669197
  };
  var map = new google.maps.Map(document.getElementById('map'), {
    center: mycompany,
    zoom: 14,
    scrollwheel: false,
    mapTypeControl: false
  });
  var contentString = '<div class="iw-content">' + '<div class="iw-subTitle">My company </div>' + '<p>455 street</p>' + '<p>City, World</p>' + '<p>Canada, Postalcode</p>' + '</div>';
  var infowindow = new google.maps.InfoWindow({
    content: contentString
  });
  var marker = new google.maps.Marker({
    position: mycompany,
    map: map,
    title: 'My company'
  });
  google.maps.event.addListener(marker, 'click', function() {
    infowindow.open(map, marker);
  });

  google.maps.event.addListener(map, 'click', function() {
    infowindow.close();
  });
}
initMap()

html,
body,
#map {
  height: 100%;
  width: 100%;
  margin: 0px;
  padding: 0px
}
       
       
         /*style the box*/  
         .gm-style .gm-style-iw {
            background-color: #252525 !important;
            top: 0 !important;
            left: 0 !important;
            width: 100% !important;
            height: 100% !important;
            min-height: 120px !important;
            padding-top: 10px;
            display: block !important;
         }    
     
         /*style the p tag*/
         .gm-style .gm-style-iw #google-popup p{
            padding: 10px;
         }
         
     
        /*style the arrow*/
        .gm-style div div div div div div div div {
            background-color: #252525 !important;
            padding: 0;
            margin: 0;
            padding: 0;
            top: 0;
            color: #fff;
            font-size: 16px;
        }
        
       

<div id="map"></div>