This is an awesome horizontal collapsible by Aysha Anggraini with html and scss. To see how it works, just click on the button Run Pen below:
How to create a horizontal collapsible
Step 1: Add Html
<body>
  <div class="container">
    <ul class="accordion">
      <li class="tabs">
        <div class="social-links twitter-icon">
          <a href="https://twitter.com/renettarenula">Twitter</a>
        </div>
        <div class="paragraph">
          <h1>Twitter</h1>
          <p>
            My thoughts in 140 characters or less. Sometimes, I do not know how
            to correctly use Twitter.
          </p>
        </div>
      </li>
      <li class="tabs">
        <div class="social-links facebook-icon">
          <a href="https://facebook.com">Facebook</a>
        </div>
        <div class="paragraph">
          <h1>Facebook</h1>
          <p>
            Where I get to stalk my friends and let them stalk me. A place to
            get people to stroke your ego.
          </p>
        </div>
      </li>
      <li class="tabs">
        <div class="social-links linkedin-icon">
          <a href="https://my.linkedin.com/pub/aysha-anggraini/49/a82/a05/"
            >LinkedIn</a
          >
        </div>
        <div class="paragraph">
          <h1>LinkedIn</h1>
          <p>
            I act totally professional on this one. It is what the recruiters
            see, you see.
          </p>
        </div>
      </li>
      <li class="tabs">
        <div class="social-links insta-icon">
          <a href="http://instagram.com/renettarenula">Instagram</a>
        </div>
        <div class="paragraph">
          <h1>Instagram</h1>
          <p>
            Where I post my duckface pictures. Occasionally, I would post
            pictures of my food and my cats.
          </p>
        </div>
      </li>
      <li class="tabs">
        <div class="social-links youtube-icon">
          <a href="https://youtube.com">Youtube</a>
        </div>
        <div class="paragraph">
          <h1>YouTube</h1>
          <p>
            Just kidding! I do not have a YouTube account. I'm not too fond of
            the camera.
          </p>
        </div>
      </li>
      <li class="tabs">
        <div class="social-links tumblr-icon">
          <a href="https://renettarenula.tumblr.com/">Tumblr</a>
        </div>
        <div class="paragraph">
          <h1>Tumblr</h1>
          <p>
            I have a tumblr but I don't really use it. I still prefer WordPress.
            I'm quite old-fashioned.
          </p>
        </div>
      </li>
      <li class="tabs">
        <div class="social-links dribbble-icon">
          <a href="http://dribbble.com">Dribbble</a>
        </div>
        <div class="paragraph">
          <h1>Dribbble</h1>
          <p>
            I do not have a Dribbble account. Would any of you be so kind and
            send me an invite?
          </p>
        </div>
      </li>
    </ul>
  </div>
</body>Step 2: Add CSS
@import 'compass/css3';
/* Updated version - 24th Nov 2014 */
@import 'compass/reset';
@import 'compass/css3';
/* Variables */
$backgroundColor: #f77462;
$list: #6dc5dd;
$border: #5ab2ca;
$geneicons: #fff;
body {
  background: $backgroundColor;
  font-family: Lato, sans-serif;
}
@font-face {
  font-family: 'Genericons';
  src: url('https://s3-us-west-2.amazonaws.com/s.cdpn.io/53819/genericons-regular-webfont.eot');
  src: url('https://s3-us-west-2.amazonaws.com/s.cdpn.io/53819/genericons-regular-webfont.woff')
      format('woff'), url('https://s3-us-west-2.amazonaws.com/s.cdpn.io/53819/genericons-regular-webfont.eot')
      format('truetype');
  font-weight: normal;
  font-style: normal;
}
[class*='genericon'] {
  display: inline-block;
  width: 16px;
  height: 16px;
  -webkit-font-smoothing: antialiased;
  font-size: 16px;
  line-height: 1;
  font-family: 'Genericons';
  text-decoration: inherit;
  font-weight: normal;
  font-style: normal;
  vertical-align: top;
}
/* IE7 */
[class*='genericon'] {
  *overflow: auto;
  *zoom: 1;
  *display: inline;
}
.container {
  margin: 100px auto;
}
.accordion {
  background: $border;
  width: 100%;
  min-width: 950px;
  display: block;
  list-style-type: none;
  overflow: hidden;
  height: 200px;
  font-size: 0;
}
.tabs {
  display: inline-block;
  background-color: $list;
  border-right: $border 1px solid;
  width: 80px;
  height: 200px;
  overflow: hidden;
  position: relative;
  margin: 0;
  font-size: 16px;
  @include transition(all 0.4s 0.1s ease-in-out);
  &:hover {
    width: 450px;
    .social-links {
      a {
        &:before {
          margin-left: -100px;
        }
        &:after {
          margin-left: -5px;
        }
      }
    }
  }
  .paragraph {
    position: relative;
    width: 360px;
    margin-left: 80px;
    padding: 50px 0 0 10px;
    height: 200px;
    background: #fff;
    h1 {
      font-size: 2.5em;
      margin-bottom: 10px;
    }
    p {
      font-size: 0.88em;
      line-height: 1.5em;
      padding-right: 30px;
    }
  }
}
.social-links {
  display: block;
  a {
    display: block;
    text-indent: -9999px;
    font-size: 0;
    line-height: 0;
    &:before,
    &:after {
      @include transition(all 0.4s 0.1s ease-in-out);
      width: 80px;
      height: 200px;
      position: absolute;
      text-indent: 0;
      padding-top: 90px;
      padding-left: 25px;
      display: block;
      font: normal 30px Genericons;
      color: $geneicons;
    }
    &:after {
      font-size: 48px;
      padding-left: 20px;
      padding-top: 80px;
      margin-left: 85px;
    }
  }
}
.twitter-icon {
  a {
    &:before,
    &:after {
      content: '\f202';
    }
    &:after {
      @include background-image(linear-gradient(#7adcf9, #4bc9f5));
    }
  }
}
.facebook-icon {
  a {
    &:before,
    &:after {
      content: '\f204';
    }
    &:after {
      @include background-image(linear-gradient(#548abf, #295b9e));
    }
  }
}
.linkedin-icon {
  a {
    &:before,
    &:after {
      content: '\f208';
    }
    &:after {
      @include background-image(linear-gradient(#00a9cd, #0083b4));
    }
  }
}
.insta-icon {
  a {
    &:before,
    &:after {
      content: '\f215';
    }
    &:after {
      @include background-image(linear-gradient(#7fc121, #298733));
    }
  }
}
.youtube-icon {
  a {
    &:before,
    &:after {
      content: '\f213';
    }
    &:after {
      @include background-image(linear-gradient(#df192a, #c41222));
    }
  }
}
.tumblr-icon {
  a {
    &:before,
    &:after {
      content: '\f214';
    }
    &:after {
      @include background-image(linear-gradient(#283e56, #325372));
    }
  }
}
.dribbble-icon {
  a {
    &:before,
    &:after {
      content: '\f201';
    }
    &:after {
      @include background-image(linear-gradient(#e03a70, #f189b8));
    }
  }
}