Smooth Collapsible Sidebar Navigation in CSS3 & Vanilla JS

A modern sidebar navigation with smooth expand & collapse transitions, written in CSS/CSS3 and vanilla JavaScript.

How to use it:

1. Create the HTML for the sidebar navigation. In this example, we’re using boxicons for essential icons.

<div class="side-bar">
  <div class="logo-name-wrapper">
    <div class="logo-name">
      <img
        src="./assets/images/logo.png"
        class="logo"
        alt="logo app"
        srcset=""
      />
      <span class="logo-name__name">Lincoln Botosh</span>
    </div>
    <button class="logo-name__button">
      <i
        class="bx bx-arrow-from-right logo-name__icon"
        id="logo-name__icon"
      ></i>
    </button>
  </div>
  <div class="message">
    <i class="message-icon bx bx-message-square-edit"></i>
    <span class="message-text">New Mesage</span>
    <span class="tooltip">New Mesage</span>
  </div>
  <ul class="features-list">
    <li class="features-item inbox active">
      <i class="bx bxs-inbox features-item-icon inbox-icon"
        ><span class="status"></span
      ></i>
      <span class="features-item-text">Inbox</span>
      <span class="inbox-number">99</span>
      <span class="tooltip">Inbox</span>
    </li>
    <li class="features-item draft">
      <i class="bx bx-file-blank features-item-icon"></i>
      <span class="features-item-text">Draft</span>
      <span class="tooltip">Draft</span>
    </li>
    <li class="features-item star">
      <i class="bx bx-star features-item-icon"></i>
      <span class="features-item-text">Starred</span>
      <span class="tooltip">Starred</span>
    </li>
    <li class="features-item sent">
      <i class="bx bx-send features-item-icon"></i>
      <span class="features-item-text">Sent</span>
      <span class="tooltip">Sent</span>
    </li>
    <li class="features-item trash">
      <i class="bx bx-trash features-item-icon"></i>
      <span class="features-item-text">Trash</span>
      <span class="tooltip">Trash</span>
    </li>
    <li class="features-item spam">
      <i class="bx bx-message-square-error features-item-icon"></i>
      <span class="features-item-text">Spam</span>
      <span class="tooltip">Spam</span>
    </li>
  </ul>
  <ul class="category-list">
    <div class="category-header">Message categories</div>
    <li class="category-item">
      <span
        class="category-item-status"
        style="background-color: #79d861"
      ></span
      ><span class="category-item-text">My works</span
      ><span class="category-item-number">9</span>
      <span class="tooltip">My works</span>
    </li>
    <li class="category-item">
      <span
        class="category-item-status"
        style="background-color: #c43c5d"
      ></span
      ><span class="category-item-text">Accountant</span
      ><span class="category-item-number">43</span>
      <span class="tooltip">Accountant</span>
    </li>
    <li class="category-item">
      <span
        class="category-item-status"
        style="background-color: #ff5050"
      ></span
      ><span class="category-item-text">Works</span
      ><span class="category-item-number">78</span>
      <span class="tooltip">Works</span>
    </li>
    <li class="category-item">
      <span
        class="category-item-status"
        style="background-color: #42ffdd"
      ></span
      ><span class="category-item-text">Marketing</span
      ><span class="category-item-number">253</span>
      <span class="tooltip">Marketing</span>
    </li>
  </ul>
  <ul class="chat-list">
    <div class="chat-header">recent chats</div>
    <button class="chat-new-btn">
      <i class="bx bxs-plus-circle chat-icon"></i>
      <span class="chat-new-btn-text">Start New Chat</span>
      <span class="tooltip">New Chat</span>
    </button>
    <li class="chat-item">
      <span class="chat-item-avatar-wrapper has-message">
        <img
          src="./assets/images/chris-evans.jpg"
          alt="avatar"
          class="chat-item-avatar"
        />
      </span>
      <span class="chat-item-name">Steve Rogers</span>
      <span class="chat-item-number">53</span>
    </li>
    <li class="chat-item">
      <span class="chat-item-avatar-wrapper">
        <img
          src="./assets/images/tony-stark.jpg"
          alt="avatar"
          class="chat-item-avatar"
        />
      </span>
      <span class="chat-item-name">Tony Stark</span
      ><span
        class="chat-item-status"
        style="background-color: #79d861"
      ></span>
    </li>
  </ul>
</div>

2. The necessary CSS styles for the sidebar navigation. Feel free to override the default CSS variables at the beginning of the following CSS snippets to create your own styles.

:root {
  --white-color: #fafafb;
  --background-color: #17171e;
  --grey-color: #b5b5be;
  --dark-grey-color: #292932;
}
.side-bar {
  width: 23.2rem;
  height: 100%;
  padding: 2.1rem 1.2rem;
  background-color: #17171e;
  position: fixed;
  transition: all 0.5s ease;
  top: 0;
}
.logo-name-wrapper {
  position: relative;
  margin-bottom: 2.1rem;
  display: flex;
  font-size: 1.2rem;
}
.logo-name {
  display: flex;
  align-items: center;
}
.logo-name__name {
  margin-left: 0.9rem;
  white-space: nowrap;
}
.logo-name__button {
  position: absolute;
  top: 50%;
  right: 0;
  font-size: 1.8rem;
  transform: translateY(-50%);
  background-color: transparent;
  border: none;
  cursor: pointer;
}
.logo-name__icon {
  font-size: 1.8rem;
  color: var(--grey-color);
}
.message {
  background-color: var(--dark-grey-color);
  display: flex;
  align-items: center;
  padding: 1.55rem 0 1.55rem 1.2rem;
  border-radius: 0.4rem;
  margin-bottom: 3.6rem;
  cursor: pointer;
  position: relative;
}
.message-icon {
  font-size: 2rem;
  transform: translateX(3rem);
  transition: all 0.5s ease;
}
.message-text {
  margin-left: 1.1rem;
  font-size: 1.4rem;
  white-space: nowrap;
  transform: translateX(3rem);
  transition: all 0.5s ease;
}
.features-list {
  padding-bottom: 1rem;
  border-bottom: 1px solid #292932;
  list-style: none;
}
.features-item {
  display: flex;
  align-items: center;
  position: relative;
  padding: 0.5rem 0.9rem;
  margin-bottom: 1.1rem;
  color: var(--grey-color);
  cursor: pointer;
  transition: 0.5s ease;
}
.features-item::before {
  transition: 0.5s ease;
  content: '';
  position: absolute;
  left: -1.2rem;
  height: 100%;
  border-left: 3px solid var(--white-color);
  border-radius: 2px;
  opacity: 0;
  visibility: hidden;
}
.features-item:hover {
  color: var(--white-color);
  transition: 0.5s ease;
}
.features-item:hover::before {
  opacity: 1;
  visibility: unset;
}
.features-item-icon {
  font-size: 2rem;
}
.features-item-text {
  margin-left: 1.5rem;
  transition: opacity 0.6s ease;
  opacity: 1;
}
.inbox-number {
  position: absolute;
  top: 50%;
  right: 0;
  transform: translateY(-50%);
  background-color: #1e75ff;
  padding: 0.5rem 0.9rem;
  border-radius: 0.4rem;
  color: var(--white-color);
  opacity: 1;
  transition: 0.6s linear;
}
.inbox-icon {
  position: relative;
}
.inbox-icon .status {
  position: absolute;
  top: 0;
  right: -1px;
  background-color: #1e75ff;
  height: 9px;
  width: 9px;
  border-radius: 50%;
  border: 2px solid var(--white-color);
  opacity: 0;
  transition: 0.6s linear;
}
.category-list {
  padding-top: 2.1rem;
  padding-bottom: 0.9rem;
  color: var(--grey-color);
  list-style: none;
  font-size: 1.2rem;
  font-weight: 500;
  border-bottom: 1px solid #292932;
}
.category-header {
  font-size: 1.2rem;
  text-transform: uppercase;
  line-height: 1.8rem;
  color: var(--white-color);
  margin-bottom: 1.3rem;
  white-space: nowrap;
}
.category-item {
  position: relative;
  padding: 0.9rem 1.1rem;
  line-height: 1.8rem;
  cursor: pointer;
  white-space: nowrap;
}
.category-item-status {
  height: 0.8rem;
  width: 0.8rem;
  border-radius: 50%;
  border: none;
  background-color: white;
  display: inline-block;
}
.category-item-text {
  margin-left: 1rem;
  transition: opacity 0.6s ease;
  opacity: 1;
}
.category-item-number {
  position: absolute;
  top: 50%;
  right: 0;
  transform: translateY(-50%);
}
.chat-list {
  padding: 2.1rem 0;
  font-size: 1.2rem;
}
.chat-header {
  text-transform: uppercase;
  line-height: 1.8rem;
  color: var(--white-color);
  margin-bottom: 1.3rem;
  white-space: nowrap;
}
.chat-new-btn {
  color: #1e75ff;
  background-color: transparent;
  outline: none;
  border: none;
  line-height: 1.8rem;
  display: flex;
  align-items: center;
  padding-bottom: 2.1rem;
  padding-left: 0.1rem;
  cursor: pointer;
  position: relative;
  font-family: 'Poppins', sans-serif;
  font-weight: 500;
}
.chat-new-btn-text {
  white-space: nowrap;
  transition: opacity 0.6s ease;
  opacity: 1;
}
.chat-icon {
  font-size: 2.1rem;
  margin-right: 1.2rem;
}
.chat-item {
  position: relative;
  display: flex;
  align-items: center;
  margin-bottom: 2.1rem;
  color: var(--grey-color);
  cursor: pointer;
}
.chat-item-avatar-wrapper {
  position: relative;
}
.chat-item-avatar-wrapper::before {
  content: '';
  position: absolute;
  top: 0;
  right: -3px;
  border-radius: 50%;
  height: 8px;
  width: 8px;
  background-color: #79d861;
  opacity: 0;
  transition: 0.6s linear;
}
.chat-item-avatar-wrapper.has-message::before {
  background-color: #1e75ff;
  border: 2px solid var(--white-color);
  height: 6px;
  width: 6px;
}
.chat-item-avatar {
  object-fit: cover;
  object-position: top;
  height: 2.1rem;
  width: 2.1rem;
  border-radius: 50%;
  border: 1px solid var(--white-color);
}
/* background color in inline style */
.chat-item-status {
  height: 0.8rem;
  width: 0.8rem;
  border-radius: 50%;
  border: none;
  background-color: white;
  position: absolute;
  top: 50%;
  right: 0;
  transform: translateY(-50%);
  margin-right: 5px;
  opacity: 1;
  transition: 0.6s linear;
}
.chat-item-number {
  position: absolute;
  top: 50%;
  right: 0;
  transform: translateY(-50%);
  background-color: #1e75ff;
  padding: 0.5rem 0.9rem;
  border-radius: 0.4rem;
  color: var(--white-color);
  opacity: 1;
  transition: 0.6s linear;
}
.chat-item-name {
  white-space: nowrap;
  transition: opacity 0.6s ease;
  opacity: 1;
  margin-left: 1.4rem;
}
.tooltip {
  position: absolute;
  top: -2.1rem;
  left: 6.4rem;
  background-color: white;
  color: var(--background-color);
  border-radius: 0.4rem;
  padding: 0.5rem 0.9rem;
  font-size: 1.4rem;
  transition: 0s;
  opacity: 0;
  display: none;
  box-shadow: 0 5px 10px rgba(0, 0, 0, 0.2);
}
.side-bar.collapse .message:hover .tooltip,
.features-item:hover .tooltip,
.category-item:hover .tooltip,
.chat-new-btn:hover .tooltip {
  top: 50%;
  transform: translateY(-50%);
  transition: all 0.5s ease;
  opacity: 1;
}
.side-bar.collapse {
  width: 6.4rem;
}
.side-bar.collapse .tooltip {
  display: block;
}
.side-bar.collapse .logo-name,
.side-bar.collapse .category-header,
.side-bar.collapse .chat-header,
.side-bar.collapse .chat-new-btn-text,
.side-bar.collapse .features-item-text,
.side-bar.collapse .inbox-number,
.side-bar.collapse .category-item-text,
.side-bar.collapse .category-item-number,
.side-bar.collapse .message-text,
.side-bar.collapse .chat-item-name,
.side-bar.collapse .chat-item-number,
.side-bar.collapse .chat-item-status {
  opacity: 0;
  pointer-events: none;
}
.side-bar.collapse .message-text {
  opacity: 0;
  pointer-events: none;
  transform: translateX(0);
}
.side-bar.collapse .message-icon {
  transform: translateX(0);
}
.side-bar.collapse .logo-name__button {
  right: 0.5rem;
}
.side-bar.collapse .inbox-icon .status,
.side-bar.collapse .chat-item-avatar-wrapper::before {
  opacity: 1;
}

3. The JavaScript to enable the expand/collapse animations.

{
  let sideBar = document.querySelector('.side-bar');
  let arrowCollapse = document.querySelector('#logo-name__icon');
  sideBar.onclick = () => {
    sideBar.classList.toggle('collapse');
    arrowCollapse.classList.toggle('collapse');
    if (arrowCollapse.classList.contains('collapse')) {
      arrowCollapse.classList =
        'bx bx-arrow-from-left logo-name__icon collapse';
    } else {
      arrowCollapse.classList = 'bx bx-arrow-from-right logo-name__icon';
    }
  };
}