.ir-arriba 
{
      display: none;
      padding: 15px;
      background: #1a2732;
      font-size: 20px;
      color: white;
      cursor: pointer;
      position: fixed;
      bottom: 40px;
      right: 15px;
      border-radius: 10px;
}

.ir-arriba:hover
{
      display: none;
      padding: 15px;
      background: #394a59;
      font-size: 20px;
      color: white;
      cursor: pointer;
      position: fixed;
      bottom: 40px;
      right: 15px;
      border-radius: 10px;
}