Step progress bar in CSS

Create simple Step progress bar in HTML, CSS and JavaScript.

HTML

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <link rel="stylesheet" href="style.css" />
    <title>Step progress bar in CSS</title>
  </head>
  <body>
    <div class="container">
      <div class="progress-container">
        <div class="progress" id="progress"></div>
        <div class="circle active">1</div>
        <div class="circle">2</div>
        <div class="circle">3</div>
        <div class="circle">4</div>
      </div>

      <button class="btn" id="prev" disabled>Prev</button>
      <button class="btn" id="next">Next</button>
    </div>
    <script src="script.js"></script>
  </body>
</html>

Output of HTML

CSS Code

@import url('https://fonts.googleapis.com/css?family=Muli&display=swap');

:root {
  --line-border-fill: #3498db;
  --line-border-empty: #e0e0e0;
}

* {
  box-sizing: border-box;
}

body {
  background-color: #f6f7fb;
  font-family: 'Muli', sans-serif;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
  overflow: hidden;
  margin: 0;
}

.container {
  text-align: center;
}

.progress-container {
  display: flex;
  justify-content: space-between;
  position: relative;
  margin-bottom: 30px;
  max-width: 100%;
  width: 350px;
}

.progress-container::before {
  content: '';
  background-color: var(--line-border-empty);
  position: absolute;
  top: 50%;
  left: 0;
  transform: translateY(-50%);
  height: 4px;
  width: 100%;
  z-index: -1;
}

.progress {
  background-color: var(--line-border-fill);
  position: absolute;
  top: 50%;
  left: 0;
  transform: translateY(-50%);
  height: 4px;
  width: 0%;
  z-index: -1;
  transition: 0.4s ease;
}

.circle {
  background-color: #fff;
  color: #999;
  border-radius: 50%;
  height: 30px;
  width: 30px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 3px solid var(--line-border-empty);
  transition: 0.4s ease;
}

.circle.active {
  border-color: var(--line-border-fill);
}

.btn {
  background-color: var(--line-border-fill);
  color: #fff;
  border: 0;
  border-radius: 6px;
  cursor: pointer;
  font-family: inherit;
  padding: 8px 30px;
  margin: 5px;
  font-size: 14px;
}

.btn:active {
  transform: scale(0.98);
}

.btn:focus {
  outline: 0;
}

.btn:disabled {
  background-color: var(--line-border-empty);
  cursor: not-allowed;
}

JavaScript

const progress = document.getElementById('progress')
const prev = document.getElementById('prev')
const next = document.getElementById('next')
const circles = document.querySelectorAll('.circle')

let currentActive = 1

next.addEventListener('click', () => {
    currentActive++

    if(currentActive > circles.length) {
        currentActive = circles.length
    }

    update()
})

prev.addEventListener('click', () => {
    currentActive--

    if(currentActive < 1) {
        currentActive = 1
    }

    update()
})

function update() {
    circles.forEach((circle, idx) => {
        if(idx < currentActive) {
            circle.classList.add('active')
        } else {
            circle.classList.remove('active')
        }
    })

    const actives = document.querySelectorAll('.active')

    progress.style.width = (actives.length - 1) / (circles.length - 1) * 100 + '%'

    if(currentActive === 1) {
        prev.disabled = true
    } else if(currentActive === circles.length) {
        next.disabled = true
    } else {
        prev.disabled = false
        next.disabled = false
    }
}