openlayers/examples/accessible.css

a.skiplink {
  position: absolute;
  clip: rect(1px, 1px, 1px, 1px);
  padding: 0;
  border: 0;
  height: 1px;
  width: 1px;
  overflow: hidden;
}
a.skiplink:focus {
  clip: auto;
  height: auto;
  width: auto;
  background-color: #fff;
  padding: 0.3em;
}
#map:focus {
  outline: #4A74A8 solid 0.15em;
}