<h1>Pure CSS Accordion <sup>2.0</sup></h1>
<div class="row">
  <div class="col">
    <h2>Open <b>multiple</b></h2>
    <div class="tabs">
      <div class="tab">
        <input type="checkbox" id="chck1">
        <label class="tab-label" for="chck1">Item 1</label>
        <div class="tab-content">
          Lorem ipsum dolor sit amet consectetur, adipisicing elit. Ipsum, reiciendis!
        </div>
      </div>
      <div class="tab">
        <input type="checkbox" id="chck2">
        <label class="tab-label" for="chck2">Item 2</label>
        <div class="tab-content">
          Lorem ipsum dolor sit amet consectetur adipisicing elit. A, in!
        </div>
      </div>
    </div>
  </div>
  <div class="col">
    <h2>Open <b>one</b></h2>
    <div class="tabs">
      <div class="tab">
        <input type="radio" id="rd1" name="rd">
        <label class="tab-label" for="rd1">Item 1</label>
        <div class="tab-content">
          Lorem, ipsum dolor sit amet consectetur adipisicing elit. Eos, facilis.
        </div>
      </div>
      <div class="tab">
        <input type="radio" id="rd2" name="rd">
        <label class="tab-label" for="rd2">Item 2</label>
        <div class="tab-content">
          Lorem ipsum dolor, sit amet consectetur adipisicing elit. Nihil, aut.
        </div>
      </div>
      <div class="tab">
        <input type="radio" id="rd3" name="rd">
        <label for="rd3" class="tab-close">Close others &times;</label>
      </div>
    </div>
  </div>
</div>
$midnight: #2c3e50;
$clouds: #ecf0f1;
// General
body {
  color: $midnight;
  background: $clouds;
  padding: 0 1em 1em;
}
h1 {
  margin: 0;
  line-height: 2;
  text-align: center;
}
h2 {
  margin: 0 0 .5em;
  font-weight: normal;
}
input {
  position: absolute;
  opacity: 0;
  z-index: -1;
}
// Layout
.row {
  display:flex;
  .col {
    flex:1;
    &:last-child {
      margin-left: 1em;
    }
  }
}
/* Accordion styles */
.tabs {
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 4px 4px -2px rgba(0,0,0,0.5);
}
.tab {
  width: 100%;
  color: white;
  overflow: hidden;
  &-label {
    display: flex;
    justify-content: space-between;
    padding: 1em;
    background: $midnight;
    font-weight: bold;
    cursor: pointer;
    /* Icon */
    &:hover {
      background: darken($midnight, 10%);
    }
    &::after {
      content: "\276F";
      width: 1em;
      height: 1em;
      text-align: center;
      transition: all .35s;
    }
  }
  &-content {
    max-height: 0;
    padding: 0 1em;
    color: $midnight;
    background: white;
    transition: all .35s;
  }
  &-close {
    display: flex;
    justify-content: flex-end;
    padding: 1em;
    font-size: 0.75em;
    background: $midnight;
    cursor: pointer;
    &:hover {
      background: darken($midnight, 10%);
    }
  }
}

// :checked
input:checked {
  + .tab-label {
    background: darken($midnight, 10%);
    &::after {
      transform: rotate(90deg);
    }
  }
  ~ .tab-content {
    max-height: 100vh;
    padding: 1em;
  }
}
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External CSS

  1. https://fonts.googleapis.com/css?family=Open+Sans:400,300,700

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