style.css

html, body {
  width: 100%;
  height: 100%;
}

html {
  font-family: sans-serif;
  color: white;
  background-color: black;
}

body {
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  align-items: center;
}

#render-canvas {
  width: 100vmin;
  height: 100vmin;
  image-rendering: pixelated;
  image-rendering: crisp-edges;
}

#control-panel {
  position: fixed;
  display: flex;
  flex-direction: column;
  top: 3rem;
  left: 3rem;
}

.control-group {
  display: flex;
  flex-direction: column;
  list-style: none;
  color: white;
  padding: 0;
  margin-top: 0;
  margin-bottom: 1rem;
}

.control {
  display: flex;
  margin-top: 2px;
}

.control input {
  display: none;
}

.control input + label,
.control.trigger {
  box-sizing: border-box;
  display: flex;
  justify-content: center;
  background-color: black;
  width: 100%;
  padding: 0.8rem 1.4rem;
  opacity: 0.5;
}

.control input:checked + label,
.control.trigger {
  opacity: 1;
}

.palette-color {
  display: inline-block;
  margin: 0 0.4em;
  width: 1em;
  height: 1em;
  border-radius: 50%;
}

#cursor {
  position: fixed;
  top: 0;
  left: 0;
  opacity: 0;
  pointer-events: none;
  width: 1px;
  height: 1px;
  fill: none;
  stroke: white;
  stroke-width: 1px;
}

#cursor svg {
  position: absolute;
  width: 100%;
  height: 100%;
  opacity: 0;
}

#cursor svg.is-visible {
  opacity: 1;
}