novnc/include/black.css

#noVNC-control-bar {
  background-color:#000;
  background-image: -webkit-gradient(
    linear,
    left bottom,
    left top,
    color-stop(0.5, rgb(0,0,0)),
    color-stop(0.5, rgb(20,20,20))
  );
  background-image: -moz-linear-gradient(
    center bottom,
    rgb(0,0,0) 50%,
    rgb(20,20,20) 50%
  );
}

.triangle-right {
  border:2px solid #fff;
  background:#000;
  color:#fff;
}

#keyboardinput {
  background-color:#000;
}