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CSS

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HTML 

              
                <div>
    <h4>Accordian</h4>
    <div class="accordian">  
        <ul> 
            <li> 
                <h3>
                    <span class="arrow"></span> Fugit Diamlorem
                </h3>
                <ul>
                    <li>
                        <p>Fugit diamlorem. Aut magni, laboriosam congue lobortis exercitation, repellat, dolor, consequatur, nobis sociosqu, culpa voluptas consectetur excepturi aptent.</p>
                        <p>Perferendis amet! Dis, ullamcorper proin aspernatur! Posuere consequat. Senectus orci turpis augue laoreet corrupti possimus, fugiat molestiae elit, ipsa sapien euismod quod! Diamlorem felis. Enim. Quibusdam rerum ipsa dis incididunt.
                            Minus nostra.</p>
                    </li>
                </ul>
            </li>
            <li>
                <h3>
                    <span class="arrow"></span> Perferendis
                </h3>
                <ul>
                    <li>
                        <p>Fugit diamlorem. Aut magni, laboriosam congue lobortis exercitation, repellat, dolor, consequatur, nobis sociosqu, culpa voluptas consectetur excepturi aptent.</p>
                    </li>
                </ul>
            </li>
            <li>
                <h3>
                    <span class="arrow"></span> Ullamcorper Proin Aspernatur
                </h3>
                <ul>
                    <li>
                        <p>Fugit diamlorem. Aut magni, laboriosam congue lobortis exercitation, repellat, dolor, consequatur, nobis sociosqu, culpa voluptas consectetur excepturi aptent.</p>
                        <p>Perferendis amet! Dis, ullamcorper proin aspernatur! Posuere consequat. Senectus orci turpis augue laoreet corrupti possimus, fugiat molestiae elit, ipsa sapien euismod quod! Diamlorem felis. Enim. Quibusdam rerum ipsa dis incididunt.
                            Minus nostra.</p>
                    </li>
                </ul>
            </li>
        </ul>
    </div> 
</div>

<div>
    <h4>Sidebar/Nav</h4>
    <div class="accordian sidebarNav">
        <ul>
            <li>
                <h3>
                    <span class="arrow"></span> Fugit Diamlorem
                </h3>
                <ul>
                    <li><a href="/">I am a link to nowhere.</a></li>
                    <li><a href="/">I am a link to nowhere.</a></li>
                    <li><a href="/">I am a link to nowhere.</a></li>
                    <li><a href="/">I am a link to nowhere.</a></li>
                </ul>
            </li>
            <li>
                <h3>
                    <span class="arrow"></span> Perferendis
                </h3>
                <ul>
                    <li><a href="/">I am a link to nowhere.</a></li>
                    <li><a href="/">I am a link to nowhere.</a></li>
                    <li><a href="/">I am a link to nowhere.</a></li>
                    <li><a href="/">I am a link to nowhere.</a></li>
                </ul>
            </li>
            <li>
                <h3>
                    <span class="arrow"></span> Ulamcorp Aspernatur
                </h3>
                <ul>
                    <li><a href="/">I am a link to nowhere.</a></li>
                    <li><a href="/">I am a link to nowhere.</a></li>
                    <li><a href="/">I am a link to nowhere.</a></li>
                    <li><a href="/">I am a link to nowhere.</a></li>
                </ul>
            </li>
            <li>
                <h3>
                    <span class="arrow"></span> Molestiae Elit
                </h3>
                <ul>
                    <li><a href="/">I am a link to nowhere.</a></li>
                    <li><a href="/">I am a link to nowhere.</a></li>
                    <li><a href="/">I am a link to nowhere.</a></li>
                    <li><a href="/">I am a link to nowhere.</a></li>
                </ul>
            </li>
        </ul>
    </div>
</div>

<div>
    <h4>Accordian - starting open</h4>
    <div class="accordian">
        <ul>
            <!-- Add 'active' class to start with a drawer already open: <li class="active"> -->
            <li class="active">
                <h3>
                    <span class="arrow"></span> Fugit Diamlorem
                </h3>
                <ul>
                    <li>
                        <p>Fugit diamlorem. Aut magni, laboriosam congue lobortis exercitation, repellat, dolor, consequatur, nobis sociosqu, culpa voluptas consectetur excepturi aptent.</p>
                        <p>Perferendis amet! Dis, ullamcorper proin aspernatur! Posuere consequat. Senectus orci turpis augue laoreet corrupti possimus, fugiat molestiae elit, ipsa sapien euismod quod! Diamlorem felis. Enim. Quibusdam rerum ipsa dis incididunt.
                            Minus nostra.</p>
                    </li>
                </ul>
            </li>
            <li>
                <h3>
                    <span class="arrow"></span> Perferendis
                </h3>
                <ul>
                    <li>
                        <p>Fugit diamlorem. Aut magni, laboriosam congue lobortis exercitation, repellat, dolor, consequatur, nobis sociosqu, culpa voluptas consectetur excepturi aptent.</p>
                    </li>
                </ul>
            </li>
            <li>
                <h3>
                    <span class="arrow"></span> Perferendis
                </h3>
                <ul>
                    <li>
                        <p>Fugit diamlorem. Aut magni, laboriosam congue lobortis exercitation, repellat, dolor, consequatur, nobis sociosqu, culpa voluptas consectetur excepturi aptent.</p>
                        <p>Perferendis amet! Dis, ullamcorper proin aspernatur! Posuere consequat. Senectus orci turpis augue laoreet corrupti possimus, fugiat molestiae elit, ipsa sapien euismod quod! Diamlorem felis. Enim. Quibusdam rerum ipsa dis incididunt.
                            Minus nostra.</p>
                    </li>
                </ul>
            </li>
        </ul>
    </div>
</div>
!

CSS 

              
                :root {
    --dark-gray: #444444;
    --light-gray: #c9c9c5;
}

.accordian {
    max-width: 600px;
    width: 100%;
    color: #b9b9b9;
    transition: all 0.2s cubic-bezier(0.25, 0.8, 0.25, 1);
    font-weight: 100;
    letter-spacing: 0.035em;
    font-size: 14px;
    margin: 0 auto;
    ul > li {
        margin-bottom: 8px;
        &:first-child h3 {
            border-top: 1px solid rgba(0, 0, 0, 0.1);
        }
    }
    h3 {
        cursor: pointer;
        background-color: #f7f9f9;
        padding: 1.2rem 1rem 1rem 1.2rem;
        margin: 0;
        border-bottom: 1px solid rgba(0, 0, 0, 0.07);
        display: block;
        font-weight: 100;
        letter-spacing: 0.035em;
        position: relative;
        font-size: 18px;
        transition: all 0.2s cubic-bezier(0.25, 0.8, 0.25, 1);
        box-shadow: 0 1px 2px rgba(0, 0, 0, 0.24);
        border-radius: 3px;
        &:hover,
        &.closed {
            color: var(--dark-gray);
            background-color: #fff;
        }
        &:hover .arrow {
            border-top: 2px solid var(--dark-gray);
            border-right: 2px solid var(--dark-gray);
        }
    }
    ul ul {
        display: none;
        height: 100%;
        margin-bottom: -7px;
        li {
            background-color: #fff;
            padding: 1rem 1.8rem;
            color: var(--dark-gray);
            box-shadow: none;
            border-left: 1px solid #dfdfdf;
            border-right: 1px solid #dfdfdf;
            border-bottom: 1px solid #dfdfdf;
            p {
                opacity: 0;
                transition: all 0.5s;
                transform: translatey(-20px);
            }
        }
        &.open p {
            opacity: 1;
            transform: translatey(0px);
        }
    }
    .arrow {
        display: inline-block;
        width: 8px;
        height: 8px;
        border-top: 2px solid var(--light-gray);
        border-right: 2px solid var(--light-gray);
        transform: rotate(135deg);
        transform-origin: center;
        float: right;
        margin-right: 8px;
        transition: transform 600ms cubic-bezier(0.175, 0.885, 0.32, 1);
        &.closed {
            margin-top: 4px;
            transform: rotate(-45deg);
            border-top: 2px solid var(--dark-gray);
            border-right: 2px solid var(--dark-gray);
        }
    }
}

// Sidebar specific
.sidebarNav {
    max-width: 300px;
    border: 1px solid #9999993b;
    h3 {
        border-radius: 0;
        box-shadow: none;
        background: none;
        margin-bottom: 0;
        &:hover,
        &.closed {
            background: none;
        }
    }
    ul > li {
        margin: 0;
    }
    ul ul li {
        padding: 0;
        background: none;
        border: 0;
        a {
            color: var(--darkgray);
            padding: 1rem 0 1rem 3em;
            display: block;
            text-decoration: none;
            &:hover {
                text-decoration: underline;
            }
        }
    } 
}


///////////////////////////////////////////////////////////////
// Layout stuff

html,
body {
    height: 100%; 
}

body {
    background-color: #eaf0f2;
    font-family: 'Josefin Sans', sans-serif;
    display: flex;
    justify-content: space-around;
    flex-wrap: wrap;
    padding: 100px 100px 800px;
    > div {
        flex: 1 1 600px;
        margin-bottom: 100px;
    }
}

ul,
ol {
    margin: 0;
    padding: 0;
}

li {
    list-style: none;
    padding: 0;
}

p {
    line-height: 1.8em;
    margin-bottom: 20px;
}

h4 {
    text-align: center;
    margin: 20px 20px 50px;
    color: orange;
    font-size: 2em;
}
!

JS 

              
                
$(function() { 
  $('.accordian li').on('click', function() {
    if ($(this).find('ul').hasClass('open')) {
      $('ul.open').slideToggle().removeClass('open');
      $('.accordian h3 span').removeClass('closed');
      $('.accordian h3').removeClass('closed');
    } else {
      $('ul.open').slideToggle().removeClass('open');
      $(this).find('ul').slideToggle().addClass('open');
      $('.accordian h3, .accordian h3 span').removeClass('closed');
      $(this).find('h3, h3 span').addClass('closed')
    }
  });
  // Active class starts one open
  $('.accordian li.active ul').slideDown().addClass('open');
});
!
999px

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