body {
  padding: 0;
  margin: 0;
  background-color: black;
  overflow: hidden;
}
#board {
  width: 100%;
  height: 100%;
  background-color: black;
  position: absolute;
}
.object {
  position: absolute;
  display: flex;
  justify-content: center;
  align-items: center;
  top: 300px;
  left: 300px;
  width: 0;
  height: 0;
}
.object > * {
  width: 80px;
  height: 80px;
  flex-shrink: 0;
  position: relative;
  box-sizing: border-box;
}
.object .source {
  width: 30px;
  height: 30px;
  border-radius: 100%;
  border: 5px #777 solid;
  color: #777;
}
.object .listener {
  border-radius: 100%;
  background-color: #48b;
  color: #48b;
  width: 50px;
  height: 50px;
}
.object .direction {
  left: 50%;
  top: -20px;
  margin-left: -5px;
  position: absolute;
  width: 10px;
  height: 10px;
  border-radius: 100%;
  background-color: currentColor;
}