<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Sidebar Menu HTML5/CSS/JS</title>
  <script src="https://kit.fontawesome.com/433b24fc29.js" crossorigin="anonymous"></script>
  <link rel="preconnect" href="https://fonts.googleapis.com">
  <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
  <link href="https://fonts.googleapis.com/css2?family=Roboto&display=swap" rel="stylesheet">
  <link rel="stylesheet" href="css/style.css">
</head>

<body>
  <div class="sidebar">
    <div class="sidebar_header">
      <i class="fa-solid fa-dragon fa-2x"></i>
    </div>

    <div class="sidebar_menu">
      <a href="#" class="sidebar_item">
        <div class="sidebar_icon">
          <i class="fa-solid fa-house"></i>
        </div>
        <h4>HOME</h4>
      </a>
      <a href="#" class="sidebar_item">
        <div class="sidebar_icon">
          <i class="fa-brands fa-steam"></i>
        </div>
        <h4>STEAM</h4>
      </a>
      <a href="#" class="sidebar_item">
        <div class="sidebar_icon">
          <i class="fa-brands fa-playstation"></i>
        </div>
        <h4>SONY</h4>
      </a>
      <a href="#" class="sidebar_item">
        <div class="sidebar_icon">
          <i class="fa-brands fa-xbox"></i>
        </div>
        <h4>XBOX</h4>
      </a>
      <a href="#" class="sidebar_item">
        <div class="sidebar_icon">
          <i class="fa-brands fa-twitch"></i>
        </div>
        <h4>TWITCH</h4>
      </a>
    </div>
  </div>

  <div class="container">
    <header class="header">
      <button class="btn-toggle"><i class="fa-solid fa-bars"></i></button>
    </header>

    <div class="content">
      <i class="fa-brands fa-fantasy-flight-games fa-10x"></i>
    </div>
  </div>

  <script src="js/script.js"></script>
</body>

</html>
/* ////////////////////
////////// CSS Variables
//////////////////// */
:root {
  --padding: 0.5rem;
  --margin-left: 0.5rem;
  --smoky-black: #12100e;
  --pine-tree: #30321c;
  --blue: #2191fb;
  --white: #ffffff;
  --font-size: 0.8rem;
}

/* ////////////////////
////////// General Styles
//////////////////// */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  text-decoration: none;
}

body {
  font-family: "Roboto", sans-serif;
}

/* ////////////////////
////////// Main container
//////////////////// */
.container {
  width: auto;
  min-height: 100vh;
  transition: margin-left 0.3s linear;
}

/* ////////////////////
////////// Sidebar Menu
//////////////////// */
.sidebar {
  width: 0;
  height: 100%;
  position: fixed;
  top: 0;
  left: 0;
  overflow: hidden;
  z-index: 1;
  background-color: var(--pine-tree);
  transition: width 0.3s linear;
}

.sidebar_header {
  width: 100%;
  height: 50px;
  display: flex;
  justify-content: center;
  align-items: center;
  text-align: center;
  color: var(--white);
}

.sidebar_menu {
  width: 100%;
  height: 100%;
}

.sidebar_item {
  width: 100%;
  padding: var(--padding);
  font-size: var(--font-size);
  background-color: var(--pine-tree);
  color: #fff;
  display: block;
  position: relative;
  white-space: nowrap;
}

.sidebar_item::before {
  content: "";
  width: 70%;
  height: 4px;
  position: absolute;
  bottom: 0;
  left: 0;
  background-color: var(--blue);
  transform: scale(0);
  transform-origin: left;
  transition: all 0.3s linear;
}

.sidebar_item:hover::before {
  transform: scale(1);
}

.sidebar_item:hover {
  background-color: #fff;
  color: var(--smoky-black);
  transition: all 0.3s linear;
}

.sidebar_item:active {
  transform: translateY(0.2rem);
}

.sidebar_icon {
  width: 20%;
  display: inline-block;
  text-align: center;
}

.sidebar_item h4 {
  width: 80%;
  display: inline-block;
}

.active {
  width: 150px;
}
.active_margin_left {
  margin-left: 150px;
}

/* ////////////////////
////////// HEADER
//////////////////// */
.header {
  width: 100%;
  height: 50px;
  display: flex;
  justify-content: start;
  align-items: center;
  background-color: var(--pine-tree);
}

/* Sidebar Toggle Button */
.btn-toggle {
  width: 50px;
  height: 25px;
  border: none;
  border-radius: 2px;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: var(--padding);
  background-color: var(--white);
  color: var(--blue);
  margin-left: var(--margin-left);
  cursor: pointer;
  transition: all 0.3s linear;
}
.btn-toggle:active {
  box-shadow: 2px 2px 5px #fff;
  outline: none;
}

/* ////////////////////
////////// Main content
//////////////////// */
.content {
  height: calc(100vh - 50px);
  background-color: var(--white);
  padding: var(--padding);
  display: flex;
  justify-content: center;
  align-items: center;
}

window.onload = load;

function load() {
  let btnToggle = document.querySelector(".btn-toggle");

  btnToggle.addEventListener("click", (e) => {
    let sidebar = document.querySelector(".sidebar");
    let container = document.querySelector(".container");
    sidebar.classList.toggle("active");
    container.classList.toggle("active_margin_left");
  });
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.