body{
  background-color: black;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;

  box-sizing: border-box;
  display:grid;
  place-items:center;
}

.slider {
  height: 120px;
  width: 250px;
  background:#333;
  border-radius:10px;
  display:grid;
  place-items:center;
}

.colorPicker {
  text-align: center;
  color: white;

  position: absolute;
  height: 100%;
}

.slider > input[type="range"] {
  width: 80%;
  height: 10px;
  border-radius: 50px;
  cursor: pointer;
  -webkit-appearance: none;
}

.slider > #red {
  background: linear-gradient(to right, black, red);
}
.slider > #green {
  background: linear-gradient(to right, black, green);
}
.slider > #blue {
  background: linear-gradient(to right, black, blue);
}