body {
  padding: 20px;
}

path.line {
  fill: none;
  stroke-width: 1px;
  stroke: teal;
  opacity: 0.025;
}

circle.letterbox {
  cursor: pointer;
}

text.letter {
  text-transform: uppercase;
  text-anchor: middle;
  font-size: 11px;
  pointer-events: none;
}