<div class="modal">
    <input id="modal" type="checkbox" class="modal--toggle">
    <label for="modal" class="modal--toggle--text">Open Modal</label>
    <div class="modal--container">
      <div class="modal--content">
        <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Minus velit maxime quam cupiditate, similique, doloribus voluptatum magnam vitae voluptatem, maiores labore explicabo dolor! Consectetur et quibusdam est corporis iusto perspiciatis!</p>
      <label class="modal--toggle--text" for="modal">Close</label>
      </div>
    </div>
  </div>

    .modal--toggle, .modal--container {
      display: none;
    }
.modal--toggle:checked ~ .modal--container {
      display: block;
    }
    .modal--container {
      position: fixed;
      z-index: 1;
      padding-top: 100px;
      left: 0;
      top: 0;
      bottom: 0;
      right: 0;
      width: 100%;
      height: 100%;
      overflow: auto;
      background-color: rgba(0,0,0,0.4); 
    }
    .modal--content {
      background-color: #fefefe;
      margin: auto;
      padding: 20px;
      border: 1px solid #888;
      width: 80%;
    }
    .modal--toggle--text {
      padding: 14px;
      border: 2px solid #fff;
      background-color: #ccc;
      cursor: pointer;
    }