style.css

.ol-control button {
  position: relative;
  top: auto;
  left: auto;
}
/*
.ol-layerswitcher > button {
  background-color: rgba(0,60,136,0.5);
}
*/
.ol-layerswitcher > button:before,
.ol-control.ol-legend > button:first-child:before,
.ol-control.ol-search button:before,
.ol-control.ol-print button:before,
.ol-control.ol-geobt button:before {
  font-family: font-gis;
  font-weight: normal;
  width: 1em;
  height: 1em;
  border: 0;
  line-height: 1em;
  border-radius: 0;
  box-shadow: none;
  top: 50%;
  left: 50%;
  transform: translate(-50%,-50%);
  background: none;
  font-size: 1.1em;
}

.ol-layerswitcher > button:before {
  content: '\ea14';
  font-family: font-ign;
  font-size: .8em;
}
.ol-control.ol-legend > button:first-child:before {
  content: '\ea85';
}
.ol-control.ol-search button:before {
  content: '\ea60';
}
.ol-control.ol-print button:before {
  content: '\ea96';
}
.ol-control.ol-geobt button:before {
  content: '\ea89';
}

.ol-layerswitcher > button:after,
.ol-control.ol-legend > button:first-child:after,
.ol-control.ol-search button:after,
.ol-control.ol-print button:after,
.ol-control.ol-geobt button:after {
  content: none;
}