<p class="rgb"></p>

<div class="main">
<div class="div">
	<div class="dot"></div>
	<div class="bar">
	</div>
</div>
</div>

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

.rgb {
  margin-bottom:2px;
  text-align: center;
  box-shadow: 0 1px 1px black;
  padding: 1rem;
  justify-content: center;
  font-weight: bold;
  height: 6vh;
  font-size: 1.2rem;
  transition: color 0.3s ease-in, font-size 0.3s ease-in;
}

.main {
  height: 94vh;
  display: grid;
  justify-content: center;
  align-items: center;
  background-color: #282828;
  transition: background-color 0.3s ease;
}

.div {
  display: flex;
  background: #404040;
  height: 10px;
  width: 400px;
  cursor: pointer;
  position: relative;
  opacity: 1;
  border-radius: 2px;
  box-shadow: 0 1px 3px black;
}

.div:hover .dot {
  opacity: 1;
}

.bar {
  height: 100%;
  z-index: 1;
  position: absolute;
  content: "";
  top: 0;
  transition: background-image 0.2s ease-in;
}

.div:hover .bar {
  background-image: linear-gradient(rgb(0, 255, 55), rgb(115, 255, 0));
}

.dot {
  opacity: 0;
  width: 15px;
  height: 15px;
  border-radius: 50%;
  z-index: 120;
  margin-left: -2px;
  margin-top: -3px;
  left: 0;
  position: absolute;
  content: "";
  top: 0;
  background-color: rgba(253, 253, 253, 0.897);
  transition: opacity 0.2s ease-out;
}

.dot::before {
  width: 3px;
  height: 40px;
  content: "";
  z-index: 0;
  top: 14px;
  left: 5px;
  position: absolute;
  background-color: rgb(0, 0, 0);
  animation: move 1s both;
  animation-iteration-count: infinite;
  animation-delay: 1s;
}

@keyframes move {
  0% {
    opacity: 0.2;
    transform: translateX(1%);
    background: rgb(60, 255, 0);
  }
  50% {
    opacity: 0.8;
    transform: translateY(10%);
    background: #ccc;
  }

  100% {
    opacity: 1;
    background: rgb(255, 255, 255);
    transform: translateY(100%);
  }
}

var div = document.querySelector(".div");
var bar = document.querySelector(".bar");
var dot = document.querySelector(".dot");
var main = document.querySelector(".main");
var rgb = document.querySelector(".rgb");
let move;

div.addEventListener("mousedown", MouseDown);

document.addEventListener("mousemove", moveMouse);

function moveMouse(e) {
  if (move) {
    MouseDown(e);
  }
}

function MouseDown(e) {
  let percentage;
  move = true;
  let j = e.clientX - div.offsetLeft;

  percentage = (100 * j) / div.clientWidth;

  bar.style.backgroundColor = "#b3b3b3";

  if (percentage > 100) {
    percentage = 100;
  }
  if (percentage < 0) {
    percentage = 0;
  }
  bar.style.width = percentage + "%";
  dot.style.left = percentage + "%";

  let gen = `rgb(${Math.round(Math.random() * 255) + 1},
    ${Math.round(Math.random() * 255) + 1},${Math.round(Math.random() * 255) +
    1})`;

  rgb.style.color = gen;
  rgb.textContent = gen;
  main.style.backgroundColor = gen;
}

document.addEventListener("mouseup", e => {
  move = false;
});