style.css

body{
    font-family: "Roboto", "Sans Serif";
    font-size: 18pt;
    color: #fff;
    background: #546e7a;
  }
  
  p{
    font-size: 12pt;
  }
  
  .wrapper{
    margin: 10% auto;
    width: 400px;
  }
  
  ul{
    list-style: none;
    margin: 0;
    padding: 0;
  }
  
  label{
    display: block;
    cursor: pointer;
    padding: 10px;
    border: 1px solid #fff;
    border-bottom: none;
  }
  
  label:hover{
    background: #29434e;
  }
  
  label.last{
    border-bottom: 1px solid #fff;
  }
  
  ul ul li{
    padding: 10px;
    background: #819ca9;
  }
  
  
  input[type="checkbox"]{
    position: absolute;
    left: -9999px;
  }
  
  input[type="checkbox"] ~ ul{
    height: 0;
    transform: scaleY(0);
  }
  
  input[type="checkbox"]:checked ~ ul{
    height: 100%;
    transform-origin: top;
    transition: transform .2s ease-out;
    transform: scaleY(1);
  }
  
  input[type="checkbox"]:checked + label{
    background: #29434e;
    border-bottom: 1px solid #fff;
  }