style.css

html,
body,
#viewDiv {
  padding: 0;
  margin: 0;
  height: 100%;
  width: 100%;
  background: linear-gradient(0deg, #f9f9f9 25%, #e2faff 75%);
  font-family: "Avenir Next W00","Helvetica Neue",Helvetica,Arial,sans-serif;
}

#menu {
  position: absolute;
  bottom: 16px;
  left: 0;
  right: 0;
  padding: 0.5em 0.5em 0 0.5em;
  background-color: rgba(255, 255, 255, 0.65);
}

button {
  font-family: "Avenir Next W00","Helvetica Neue",Helvetica,Arial,sans-serif;
  font-size: 1em;
  background: none;
  border: none;
  border-bottom: 1px solid rgb(100, 100, 100);
  padding: 0;
}

button:hover {
  background: rgb(100, 100, 100);
  color: white;
  cursor: pointer;
}

.credits {
  font-size: 12px;
  margin-bottom: 0;
}

.legend-label {
  font-weight: bold;
}

canvas {
  filter: opacity(0);
  transition: filter 1s;
}

.snow {
  pointer-events: none;
  position: absolute;
  top: 0;
  height: 100%;
  width: 100%;
  display: none;
}

#loader {
  position: absolute;
  top: 50%;
  margin-top: -100px;
  text-align: center;
  width: 100%;
}

#loader>img {
  height: 70px;
  filter: drop-shadow(1px 1px 2px rgba(100, 100, 100, 0.6));
}

.i-large,
.i-medium,
.i-small {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
}

.i-large {
  background: url("./img/snow_large.png") repeat 0px 0px;
  animation: dropSnowFlakes 2s linear infinite;
}
.i-medium {
  background: url("./img/snow_medium.png") repeat 0px 0px;
  animation: dropSnowFlakes 12s linear infinite;
}
.i-small {
  background: url("./img/snow_small.png") repeat 0px 0px;
  animation: dropSnowFlakes 27s linear infinite;
}

@keyframes dropSnowFlakes {
  from {
    background-position: 0 0;
  }
  to {
    background-position: 0 413px;
  }
}