Pure CSS Responsive Horizontal Accordion

A responsive horizontal accordion created by ferry that makes use of CSS3 transitions and transforms to smoothly expand accordion items on mouse hover.

How to use it:

Build the Html structure for the horizontal accordion using Html lists.

<div class="accordion">
  <ul>
    <li>
      <div> <a href="#">
        <h2>Title 1</h2>
        <p>Content 1</p>
        </a> </div>
    </li>
    <li>
      <div> <a href="#">
        <h2>Title 2</h2>
        <p>Content 2</p>
        </a> </div>
    </li>
    <li>
      <div> <a href="#">
        <h2>Title 3</h2>
        <p>Content 3</p>
        </a> </div>
    </li>
    <li>
      <div> <a href="#">
        <h2>Title 4</h2>
        <p>Content 4</p>
        </a> </div>
    </li>
    <li>
      <div> <a href="#">
        <h2>Title 5</h2>
        <p>Content 5</p>
        </a> </div>
    </li>
    <li>
      <div> <a href="#">
        <h2>Title 6</h2>
        <p>Content 6</p>
        </a> </div>
    </li>
  </ul>
</div>

The basic CSS styles for the accordion.

.accordion {
  width: 100%;
  max-width: 1080px;
  height: 250px;
  overflow: hidden;
  margin: 50px auto;
}
.accordion ul {
  width: 100%;
  display: table;
  table-layout: fixed;
  margin: 0;
  padding: 0;
}
.accordion ul li {
  display: table-cell;
  vertical-align: bottom;
  position: relative;
  width: 16.666%;
  height: 250px;
  background-repeat: no-repeat;
  background-position: center center;
  transition: all 500ms ease;
}
.accordion ul li div {
  display: block;
  overflow: hidden;
  width: 100%;
}
.accordion ul li div a {
  display: block;
  height: 250px;
  width: 100%;
  position: relative;
  z-index: 3;
  vertical-align: bottom;
  padding: 15px 20px;
  box-sizing: border-box;
  color: #fff;
  text-decoration: none;
  font-family: Open Sans, sans-serif;
  transition: all 200ms ease;
}
.accordion ul li div a * {
  opacity: 0;
  margin: 0;
  width: 100%;
  text-overflow: ellipsis;
  position: relative;
  z-index: 5;
  white-space: nowrap;
  overflow: hidden;
  -webkit-transform: translateX(-20px);
  transform: translateX(-20px);
  -webkit-transition: all 400ms ease;
  transition: all 400ms ease;
}
.accordion ul li div a h2 {
  font-family: Montserrat, sans-serif;
  text-overflow: clip;
  font-size: 24px;
  text-transform: uppercase;
  margin-bottom: 2px;
  top: 160px;
}
.accordion ul li div a p {
  top: 160px;
  font-size: 13.5px;
}

Add background images to the accordion items.

.accordion ul li:nth-child(1) { background-image: url("1.jpg"); }
.accordion ul li:nth-child(2) { background-image: url("2.jpg"); }
.accordion ul li:nth-child(3) { background-image: url("3.jpg"); }
.accordion ul li:nth-child(4) { background-image: url("4.jpg"); }
.accordion ul li:nth-child(5) { background-image: url("5.jpg"); }
.accordion ul li:nth-child(6) { background-image: url("6.jpg"); }

Expand the accordion item on mouse hover using :hover pseudo element.

.accordion ul:hover li { width: 8%; }
.accordion ul:hover li:hover { width: 60%; }
.accordion ul:hover li:hover a { background: rgba(0, 0, 0, 0.4); }
.accordion ul:hover li:hover a * {
  opacity: 1;
  -webkit-transform: translateX(0);
  transform: translateX(0);
}

Make the accordion responsive using CSS media queries.

@media screen and (max-width: 600px) {
.accordion { height: auto; }
.accordion ul li,
.accordion ul li:hover,
.accordion ul:hover li,
.accordion ul:hover li:hover {
  position: relative;
  display: table;
  table-layout: fixed;
  width: 100%;
  -webkit-transition: none;
  transition: none;
}
}