body {
  height: 100%;
  padding: 0;
  margin: 0;
}
path, circle {
  fill: none;
  stroke: rgba(110,120,200,.25);
  stroke-width: 13px;
}
svg {
  background-color: black;
}
circle {
  fill: rgba(220,220,10,.75);
}
.controls {
  position: absolute;
  top: 10px;
  left: 10px;
  z-index: 10;
  opacity: .4;
}
button:hover { 
  opacity: 1;
  cursor: pointer;
}

h2 {
  color: orange;
}
.plusplus {
  fill: rgba(255,255,0,1);
}
.plusminus {
  fill: rgba(255,70,0,.75);
}
.minusminus {
  fill: rgba(70,70,0,.25);
}
.minusplus {
  fill: rgba(70,255,0,.75);
}